Which of the following does NOT describe the Image formed by a plane minor?

Same distance from mirror as object

The differences observed in solids, liquids and gases may be accounted for by

the spacing and forces acting between the molecules

the different molecules in each of them

A positively charged rod X is brought near an uncharged metal sphere Y and is then touched by a finger with X still in place. When the finger is removed, the result is that Y has

a negative charge and a negative potential

a positive charge and a zero potential

a negative charge and a positive potential

a negative charge and a negative potential

Temperature is the property of a body which is proportional to the ____.

average kinetic energy of its molecules

total kinetic energy of its molecules

average kinetic energy of its molecules

A narrow beam of white light can be split up into different colours by a glass prism. The correct explanation is that

different colours of white light travel with different speeds in glass

white light Is an electromagnetic wave

the prism has all the colours of the white light

different colours of white light travel with different speeds in glass

white light has undergone total Internal reflection in the prism

Convex mirrors are used as driving mirrors because images formed are

inverted, virtual and diminished

Which of the following is true of an electrical charge?

Positive charge means deficit electrons

Negative charge means excess of electrons

electric current means movement of electrons

The time rate of loss of heat by a body is proportional to the

difference in temperature between the body and its surroundings

temperature of its surroundings

difference in temperature between the body and its surroundings

ratio of the temperature of the body to that of its surroundings

In homes, electrical appliances and lamps are connected in parallel because

series connection uses high voltage

parallel connection does not heat up the wires

series connection uses high voltage

Natural radioactivity consists of the emission of

α- particles, β - rays and g-rays

Which of the following best describes the energy changes which take place when a steam engine drives a generator which lights a lamp?

heat ----> Kinetic ----> Electricity ----> Heat and Light

heat ----> Light----> Sound ----> Kinetic

Kinetic ----> Light ----> Heat ----> Electricity

heat ----> Kinetic ----> Electricity ----> Heat and Light

electricity ----> Kinetic ----> Heat ----> Light

JAMB UTME - Physics - 2018 | Green Bridge CBT

Pregunta 1 Informe

In the diagram given the hanging mass m2 is adjusted until m1 is on the verge of sliding. The coefficient of static

m₁

m₂

m₁	g
m₂

m₂

m₁

m₂	g
m₁

Detalles de la respuesta

I think the correct option is C (

\frac{m_{2}}{m_{1}}

). The coefficient of friction is a ratio of two forces and hence g will cancel out.

Lee la nota de la lección en Liquids At Rest (JAMB)

Liquids At Rest

Ver respuesta

Pregunta 2 Informe

The photo cell works on the principle of the

Voltaic cell

Emission of electron by incident radiation

Emission of protons by incident radiation

Photographic plate

Detalles de la respuesta

The photocell works on the principle of the emission of electrons by incident radiation. In simple terms, a photocell is a device that converts light energy into electrical energy. It does this by using a material (such as silicon) that releases electrons when it is exposed to light. These electrons can then be collected and used to produce a current, which can be used to power an electrical device. The more light that hits the photocell, the more electrons are released and the greater the electrical current.

Lee la nota de la lección en Electrostatics (JAMB)

Electrostatics

Ver respuesta

Pregunta 3 Informe

Which of the following statements are TRUE of isotopes?

I. Isotopes of an element have the same chemical properties because they have the same number of electrons

II. Isotopes of elements are normally separated using physical properties

III. Isotopes of an element have the same number of protons in their nuclei

I and II only

I and III only

II and III only

I, II and III

Detalles de la respuesta

The correct answer is "I and III only". Isotopes of an element have the same number of protons in their nuclei, meaning they have the same atomic number and are therefore the same element. Because of this, they have the same chemical properties. However, isotopes of an element have different numbers of neutrons in their nuclei, which means they have different atomic masses. This is why isotopes can be separated using physical properties such as their mass or other characteristics related to their mass.

Lee la nota de la lección en Structure Of The Atom (Nigeria Only) (WAEC)

Structure Of The Atom (Nigeria Only)

Ver respuesta

Pregunta 4 Informe

In the diagram shown, which of the simple pendulum will resonate with P when set into oscillation?

U

T

R and T

Q and R

Equilibrium Of Forces

Ver respuesta

Pregunta 5 Informe

The process by which protons are converted into helium atoms with a tremendous release of energy is called?

thermionic emission

nuclear fission

thermonuclear fusion

photoelectric emission

Detalles de la respuesta

The process by which protons are converted into helium atoms with a tremendous release of energy is called "thermonuclear fusion". In this process, two light atomic nuclei combine to form a heavier nucleus, releasing a huge amount of energy in the form of light and heat. This is the same process that powers the sun and other stars. The high temperatures and pressures required for fusion to occur can only be achieved in stars or in controlled environments such as fusion reactors. Thermonuclear fusion is different from nuclear fission, which is the process of splitting a heavy nucleus into lighter nuclei with the release of energy. Thermionic emission and photoelectric emission are different processes that involve the emission of electrons from a material due to heating or exposure to light, respectively.

Lee la nota de la lección en Structure Of The Atom (Nigeria Only) (WAEC)

Structure Of The Atom (Nigeria Only)

Ver respuesta

Pregunta 6 Informe

A 40W instrument has a resistance 90 Ohms. On what voltage should it be operated normally

60V

150V

225V

360V

Detalles de la respuesta

To calculate the voltage needed for a 40W instrument with a resistance of 90 Ohms, we can use the formula: Voltage = √(Power x Resistance) Plugging in the given values, we get: Voltage = √(40W x 90Ω) Voltage = √(3600) Voltage = 60V Therefore, the instrument should be operated at 60V to generate 40W of power with a resistance of 90 Ohms. The correct answer is, 60V.

Lee la nota de la lección en Current Electricity (JAMB)

Lee la nota de la lección en Simple A.C Circuits (JAMB)

Current Electricity

Simple A.C Circuits

Ver respuesta

Pregunta 7 Informe

In the diagram given if the atmospheric pressure is 760mm, the pressure in the chamber G Is

660mm

890mm

690mm

860mm

Pressure

Ver respuesta

Pregunta 8 Informe

The amount of heat needed to raise the temperature of 10kg of Copper by 1K is its

specific heat capacity

latent heat

heat capacity

internal energy

Detalles de la respuesta

The correct answer is "specific heat capacity." Specific heat capacity is a measure of how much heat energy is required to raise the temperature of a certain amount of a substance by 1 degree Celsius (or 1 Kelvin, which is the same size as 1 degree Celsius). In this case, we are dealing with 10kg of copper, so we need to know the specific heat capacity of copper. The specific heat capacity of copper is 0.385 J/g°C (joules per gram per degree Celsius). To calculate the amount of heat needed to raise the temperature of 10kg of copper by 1K, we need to know the total mass of copper (10kg) and the specific heat capacity of copper (0.385 J/g°C). The formula for calculating the amount of heat energy required is: Heat energy = mass x specific heat capacity x change in temperature Since we want to raise the temperature by 1K, the change in temperature is 1K. So, the amount of heat energy required to raise the temperature of 10kg of copper by 1K is: Heat energy = 10kg x 0.385 J/g°C x 1K = 3.85 kJ Therefore, it takes 3.85 kilojoules (kJ) of heat energy to raise the temperature of 10kg of copper by 1K.

Lee la nota de la lección en Quantity Of Heat (JAMB)

Lee la nota de la lección en Temperature And Its Measurement (JAMB)

Quantity Of Heat

Temperature And Its Measurement

Ver respuesta

Pregunta 9 Informe

The pitch of an acoustic device can be increased by

decreasing the loudness

increasing the intensity

increasing the frequency

decreasing the intensity

Detalles de la respuesta

The pitch of an acoustic device refers to the perceived highness or lowness of a sound, and is determined by the frequency of the sound wave. To increase the pitch of an acoustic device, you need to increase the frequency of the sound wave. This can be done by increasing the number of vibrations per second that the device produces. So, the correct answer is to "increase the frequency".

Lee la nota de la lección en Current Electricity (JAMB)

Lee la nota de la lección en Sound Waves (WAEC)

Current Electricity

Sound Waves

Ver respuesta

Pregunta 10 Informe

A room is heated by means of a charcoal fire, an occupants of the room standing away from the fire is warmed mainly by

Convection

Radiation

Conduction

Reflection

Detalles de la respuesta

The main way that the occupants of a room standing away from a charcoal fire are warmed is by radiation. Radiation is the transfer of heat energy through electromagnetic waves, and it can travel through empty space. In this scenario, the charcoal fire emits radiation in the form of infrared waves, which travel through the air and warm up the objects (including the occupants) in the room. Convection, on the other hand, is the transfer of heat through the movement of fluids (such as air), but in this case, the air in the room is not being actively circulated by a fan or other mechanism. Conduction involves the transfer of heat through direct contact between two objects, but the occupants are not in direct contact with the fire. Reflection refers to the bouncing of radiation off a surface, but it is not a significant factor in this scenario as most of the radiation is absorbed by the objects in the room.

Lee la nota de la lección en Heat Transfer (JAMB)

Lee la nota de la lección en Gravitational Field (WAEC)

Lee la nota de la lección en Conduction Of Electricity Through (JAMB)

Heat Transfer

Gravitational Field

Conduction Of Electricity Through

Ver respuesta

Pregunta 11 Informe

The process whereby a liquid turns spontaneously into vapour is called

regelation

evaporation

boiling

sublimation

Detalles de la respuesta

The process whereby a liquid turns spontaneously into vapor is called evaporation. Evaporation is the process by which a liquid changes into a gas at a temperature below its boiling point. This happens when the molecules of the liquid gain enough energy to escape from the surface of the liquid into the air as a gas. The rate of evaporation depends on factors such as the temperature, the humidity of the air, and the surface area of the liquid. For example, a shallow pool of water will evaporate faster than a deep one because it has a larger surface area. Boiling, on the other hand, is the process by which a liquid changes into a gas at its boiling point. This happens when the pressure of the gas generated by the boiling liquid is equal to the atmospheric pressure. The temperature remains constant during boiling. Regelation and sublimation are different processes altogether. Regelation is the process by which a solid changes into a liquid when it is subjected to pressure. Sublimation is the process by which a solid changes directly into a gas, bypassing the liquid state.

Lee la nota de la lección en Vapours (JAMB)

Vapours

Ver respuesta

Pregunta 12 Informe

Calculate the effective capacitance of the circuit in the diagram given

4μf

3μf

2μf

1μf

Detalles de la respuesta

The three 2uf capacitors are in parallel to each other so u add them like this
2uf+2uf+2uf=6uf
So u have three capacitors in series
6uf 2uf and 3uf
They are in series so
1/C= 1/6+1/3=1/2
C=2uf
Then the same thing with the last two capay
1/2+1/2=1uf
Thanks

Ver respuesta

Pregunta 13 Informe

A boy receives the echo of his clap reflected by a nearby hill 0.8s later. If the speed of sound in air is 3.40ms$^{-1}$, how far is he from the hill?

66m

136m

264m

528m

Detalles de la respuesta

The speed of sound in air is given as 3.40 m/s. The echo of the clap is heard 0.8 seconds after it was produced, which means it traveled to the hill and back. The time taken for sound to travel to the hill is half of the time taken for it to travel to and from the hill. Therefore, the time taken for sound to travel to the hill is 0.8/2 = 0.4 seconds. We can use the formula: distance = speed x time to calculate the distance between the boy and the hill. distance = speed of sound x time taken for sound to travel to the hill distance = 3.40 m/s x 0.4 s distance = 1.36 m Therefore, the distance between the boy and the hill is 1.36 meters. However, the answer options provided are in meters and are significantly larger than 1.36 meters. It is possible that the speed of sound provided in the question is incorrect or the answer options are incorrect.

Ver respuesta

Pregunta 14 Informe

The tendency of a body to remain at rest when a force is applied to it is called.

Impulse

Momentum

Inertia

Friction

Detalles de la respuesta

The tendency of a body to remain at rest or to continue moving with a constant velocity (in a straight line at a constant speed) when no force is acting on it is called inertia. Inertia is a property of matter, and the amount of inertia depends on the mass of an object. Inertia can also be thought of as a resistance to changes in motion, meaning that an object at rest will tend to stay at rest, and an object in motion will tend to stay in motion unless acted upon by an external force. This property of inertia is what makes it difficult to start, stop, or change the direction of motion of an object. The force required to overcome the inertia of an object depends on the mass of the object and the magnitude of the acceleration desired. Therefore, the greater the mass of an object, the greater its inertia, and the more force required to change its motion.

Lee la nota de la lección en Scalars And Vectors (WAEC)

Lee la nota de la lección en Equilibrium Of Forces (WAEC)

Scalars And Vectors

Equilibrium Of Forces

Ver respuesta

Pregunta 15 Informe

The friction which exist between two layers of liquid in relative motion is called

Capillary

Surface

Viscosity

Cohesion

Detalles de la respuesta

The correct answer is "Viscosity". Viscosity is the property of a fluid that describes its resistance to flow. When two layers of liquid are in relative motion, the viscosity of the liquid causes friction between the layers. This friction creates a resistance to the movement of one layer past the other. The greater the viscosity of the liquid, the greater the friction and the more difficult it is for the layers to move past each other. This property is important in many industrial and natural processes, such as the flow of oil in pipelines or the movement of blood through the human body.

Lee la nota de la lección en Friction (JAMB)

Lee la nota de la lección en Properties Of Waves: Reflection, Refraction, Diffraction (WAEC)

Friction

Properties Of Waves: Reflection, Refraction, Diffraction

Ver respuesta

Pregunta 16 Informe

If the focal length of a camera is 20cm, the distance from the film at which the lens must be set to produce a sharp image of 100cm away is

17cm

20cm

25cm

100cm

Detalles de la respuesta

F = 20cm
V = 100cm
U = ?

\frac{1}{U}

+

\frac{1}{V}

=

\frac{1}{F}

\frac{1}{20}

+

\frac{1}{100}

=

\frac{1}{F}

\frac{5 + 1}{100}

=

\frac{1}{F}

F =

\frac{100}{6}

= 16.7cm
= 17cm

Lee la nota de la lección en Vapours (JAMB)

Vapours

Ver respuesta

Pregunta 17 Informe

What type of reaction is represented by the following scheme?

$ {}_{1}^{2}X + {}_{1}^{2}Y \longrightarrow {}_{2}^{3}Z + {}_{1}^{0}n + \text{energy} $

fusion reaction

fission reaction

Chain reaction

radioactive decay

Detalles de la respuesta

The type of reaction represented by the given scheme is a nuclear fission reaction. Nuclear fission is a process where a heavy nucleus is split into smaller nuclei with the release of energy. In the given scheme, a heavy element X is split into two lighter elements, Y and Z, along with the release of energy and some neutrons (n). In a nuclear fission reaction, a neutron is usually absorbed by the nucleus of the heavy element, which then becomes unstable and splits into two smaller nuclei and some neutrons. These neutrons can then go on to split other heavy nuclei, resulting in a chain reaction. In the given scheme, the release of energy and the presence of neutrons suggest that it is a fission reaction. Moreover, the scheme depicts the process of splitting a heavy element into two lighter elements, which is a characteristic of a fission reaction. Therefore, the type of reaction represented by the given scheme is a nuclear fission reaction.

Ver respuesta

Pregunta 18 Informe

An object is placed 20cm from a concave mirror of focal length 10cm. The linear magnification of the image produced is?

0

1

2

1

2

Detalles de la respuesta

The linear magnification of an image is given by the formula: magnification = height of image / height of object = -v/u where v is the image distance, u is the object distance, and the negative sign indicates that the image is inverted. In this problem, the object is placed 20cm from a concave mirror of focal length 10cm. Since the object is placed beyond the focal point, the image will be real and inverted. Using the mirror formula 1/f = 1/v + 1/u, we can find the image distance v: 1/10 = 1/v + 1/20 Solving for v, we get: v = -20 cm Now, we can use the magnification formula to find the linear magnification: magnification = -v/u = -(-20)/20 = 1 Therefore, the linear magnification of the image produced is 1, which means the image is the same size as the object and is also inverted. The answer is: 1.

Lee la nota de la lección en Electrostatics (JAMB)

Electrostatics

Ver respuesta

Pregunta 19 Informe

Musical instruments playing the same note can be distinguished from one another owing to the difference in their

quality

pitch

intensity

loudness

Detalles de la respuesta

Different musical instruments playing the same note can be distinguished from one another due to the difference in their "timbre" or "tone color." Timbre refers to the unique character or quality of a sound that allows us to distinguish it from other sounds even when they have the same pitch and loudness. For example, a piano and a guitar playing the same note will sound different due to the differences in their timbre. This is why we can tell the difference between different instruments and why some instruments are better suited to certain styles of music than others.

Ver respuesta

Pregunta 20 Informe

Electrical power is transmitted at a high voltage rather than a low voltage because the amount of energy loss is due to

Heat dissipation

Production of eddy currents

Excessive current discharge

Excessive voltage discharge

Detalles de la respuesta

The primary reason that power is transmitted at high voltages is to increase efficiency. As electricity is transmitted over long distances, there are inherent energy losses along the way. High voltage transmission minimizes the amount of power lost as electricity flows from one location to the next. How? The higher the voltage, the lower the current. The lower the current, the lower the resistance losses in the conductors. And when resistance losses are low, energy losses are low also. Electrical engineers consider factors such as the power being transmitted and the distance required for transmission when determining the optimal transmission voltage

Ver respuesta

Pregunta 21 Informe

Cathode rays are

High-energy electromagnetic waves

protons

neutrons

streams of electrons

Detalles de la respuesta

Cathode rays are streams of electrons. They were first discovered by scientists experimenting with vacuum tubes, and they observed that a glowing beam of particles traveled from the negatively charged electrode (the cathode) to the positively charged electrode (the anode). These particles were found to have a negative charge, which was later identified as electrons. Cathode rays played an important role in the development of electronics and the understanding of atomic structure.

Lee la nota de la lección en Electric Field (WAEC)

Lee la nota de la lección en Electromagnetic Field (Part 2) (WAEC)

Electric Field

Electromagnetic Field (Part 2)

Ver respuesta

Pregunta 22 Informe

The efficiency of energy conversion on the energy flow through a hydroelectric power is?

E1

E2

\frac{E 3}{E 2}

\frac{E 2}{E 1}

+ E2

\frac{E 2}{E 3}

+ E1

Detalles de la respuesta

Efficiency =

\frac{useful energy output from machine}{energy input into machine}

=

\frac{E 3}{E 2}

Lee la nota de la lección en Work, Energy And Power (WAEC)

Work, Energy And Power

Ver respuesta

Pregunta 23 Informe

What flows to the earth by connecting the conductor to the earth?

Electrons

Ion

Neutron

Proton

Detalles de la respuesta

When a conductor is connected to the earth, electrons flow to the earth. Electrons are negatively charged particles that are present in all conductors. When a conductor is connected to the earth, it creates a path for electrons to flow from the conductor to the earth, which helps to balance the electric potential and prevent the buildup of electric charge. This flow of electrons is known as grounding and is an important safety measure in electrical systems.

Lee la nota de la lección en Electrostatics (JAMB)

Electrostatics

Ver respuesta

Pregunta 24 Informe

The resistance of a 40W car head lamp, drawing current from a 12V battery is ____.

0.3Ω

3.3Ω

3.6Ω

4.8Ω

Detalles de la respuesta

The resistance of a 40W car headlamp can be calculated using Ohm's Law, which states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points, and inversely proportional to the resistance (R) of the conductor. The equation can be written as V = IR. Since the power (P) of the headlamp is given as 40W and the voltage is 12V, we can calculate the current using the equation P = IV. Substituting I = P/V, we get I = 40/12 = 3.33A. Finally, using Ohm's Law, we can calculate the resistance as R = V/I = 12/3.33 = 3.6Ω. So, the resistance of the 40W car headlamp, drawing current from a 12V battery, is 3.6Ω.

Lee la nota de la lección en Current Electricity (JAMB)

Current Electricity

Ver respuesta

Pregunta 25 Informe

Mercury which is spilled onto a glass surface forms ball-like shapes because____.

Mercury is a metal

The cohesive force between its molecules is greater than the adhesive force between mercury and glass molecules

The cohesive force between its molecules is less than the adhesive force between mercury and glass molecules

The viscosity of mercury is height

Detalles de la respuesta

In case of small drops of mercury, the gravitational potential energy is negligible in comparison to the potential energy due to surface tension.Consequently, to keep the drop in equilibrium, the mercury drop’s surface tends to contract so that its surface area will be the least for a sphere and the drops will be spherical.
But in the case of bigger drops of mercury, the potential energy due to gravity is predominant over the potential energy due to surface tension.Consequently, to keep equilibrium , the mercury drop tends to assume minimum potential energy as possible, the drop becomes oval in shape and lower center of gravity.

Lee la nota de la lección en Liquids At Rest (JAMB)

Liquids At Rest

Ver respuesta

Pregunta 26 Informe

Which of the following phenomena cannot be explained by the molecular theory of matter?

Conduction

Convection

Expansion

Radiation

Detalles de la respuesta

Conduction: the flow of internal energy from a region of higher temperature to lower temperature
Convection: heat transfer due to bulk movement of molecules within fluids
Expansion: the action of becoming larger or more extensive

Lee la nota de la lección en Thermal Expansion (JAMB)

Thermal Expansion

Ver respuesta

Pregunta 27 Informe

A lens of focal length 15cm forms on erect image which is three times the size of the object. The distance between the object and the image is ___.

10cm

20cm

30cm

40cm

Detalles de la respuesta

We can use the lens formula, 1/f = 1/v - 1/u, where f is the focal length of the lens, v is the distance between the lens and the image, and u is the distance between the lens and the object. From the problem, we know that the focal length of the lens is 15 cm, and the image is erect and three times the size of the object. This means that the image distance v is positive and the object distance u is negative (since the object is in front of the lens). Let's assume that the object distance u is -x cm, where x is a positive number. Then, the image distance v is +3x cm, since the image is three times the size of the object. Substituting these values into the lens formula, we get: 1/15 = 1/(+3x) - 1/(-x) Simplifying the right-hand side, we get: 1/15 = (1 + 3)/3x Multiplying both sides by 3x, we get: 3x/15 = 4 Simplifying, we get: x = 20 Therefore, the distance between the object and the lens is -20 cm (since it is in front of the lens), and the distance between the image and the lens is +60 cm (since it is behind the lens). The distance between the object and the image is the sum of these distances, which is: (-20) + (+60) = 40 cm Therefore, the answer is 40cm.

Lee la nota de la lección en Optical Instruments (JAMB)

Optical Instruments

Ver respuesta

Pregunta 28 Informe

Which of the following is the dimension of pressure

ML

^{- 1}

T

^{- 2}

MLT

^{- 2}

ML

^{2}

T

^{3}

ML

^{- 3}

Detalles de la respuesta

The dimension of pressure is ML^-1T^-2 Pressure is defined as the force per unit area. This means that pressure is dependent on the force applied and the area over which it is applied. The unit of force is measured in Newtons (N), and the unit of area is measured in square meters (m²). Therefore, the unit of pressure is N/m², which is also known as Pascals (Pa). To determine the dimension of pressure, we need to break down the units into their fundamental dimensions of mass (M), length (L), and time (T). Force is measured in N, which is kg m/s². Area is measured in m², which is L². Therefore, the dimension of pressure can be calculated as (kg m/s²)/(L²), which simplifies to ML^-1T^-2.

Ver respuesta

Pregunta 29 Informe

The energy needed to move a unit positive charge around a complete electric circuit is called the

electromotive force

electric potential difference

electric energy

kinetic energy

Detalles de la respuesta

The energy needed to move a unit positive charge around a complete electric circuit is called the "electromotive force", also known as "emf". This is because the emf is what drives the flow of electric charge, or current, around the circuit. Think of it like a battery in a flashlight. The battery provides the emf that drives the flow of electric current through the wires and the light bulb. Without the emf from the battery, the electric charges wouldn't be able to flow and the light wouldn't turn on. The other answer options, such as electric potential difference and electric energy, are related to the emf but don't specifically refer to the energy needed to move a unit positive charge around a circuit. Kinetic energy, on the other hand, is not related to the movement of electric charges around a circuit at all.

Lee la nota de la lección en Heat Energy (WAEC)

Lee la nota de la lección en Properties Of Waves: Reflection, Refraction, Diffraction (WAEC)

Lee la nota de la lección en Introductory Electronics (JAMB)

Heat Energy

Properties Of Waves: Reflection, Refraction, Diffraction

Introductory Electronics

Ver respuesta

Pregunta 30 Informe

The product of force and time is?

Impulse

Momentum

Inertia

Friction

Detalles de la respuesta

The product of force and time is known as impulse. Impulse can be defined as the change in momentum that an object experiences as a result of a force being applied to it over a period of time. In simpler terms, impulse is the "push" that an object receives from a force acting on it for a certain amount of time. The more force applied, or the longer the time the force is applied, the greater the impulse and the greater the change in momentum of the object. It's important to note that impulse is a vector quantity, meaning it has both magnitude and direction. Impulse is a measure of the ability of a force to cause an object to change its velocity, and can be used to explain many phenomena in physics, such as why a heavy object is harder to stop than a lighter one, or why a soccer ball changes direction when it is kicked.

Lee la nota de la lección en Work, Energy And Power (WAEC)

Work, Energy And Power

Ver respuesta

Pregunta 31 Informe

Electrical appliances in homes are normally earthed so that

a person touching the appliances is safe from electric shock

both the a.c. and d.c. sources can be used

the appliances are maintained at a higher pd than the earth

the appliances are maintained at a lower pd than the earth

Detalles de la respuesta

Electrical appliances in homes are normally earthed so that a person touching the appliances is safe from electric shock. Earthing provides a safety mechanism by connecting the metal case of an electrical appliance to the earth through a conductor. In the event of a fault in the appliance, such as a short circuit, the current will flow through the earth wire instead of the person's body, preventing electric shock. By connecting the metal case of an appliance to the earth, the potential difference (PD) between the appliance and the earth is reduced to zero, ensuring that the appliance is maintained at a lower PD than the earth. Therefore, "the appliances are maintained at a lower pd than the earth" is the correct answer.

Lee la nota de la lección en Electrostatics (JAMB)

Electrostatics

Ver respuesta

Pregunta 32 Informe

A ball of mass 5.0kg hits a smooth vertical wall normally with a speed of $2\text{ms}^{-1}$. Determine the magnitude of the resulting impulse

20.0kgms

^{- 1}

10.0kgms

^{- 1}

5.0kgms

^{- 1}

2.5kgms

^{- 1}

Detalles de la respuesta

The magnitude of the resulting impulse can be calculated using the formula impulse = change in momentum. In this scenario, the ball experiences a change in velocity (speed) as it hits the wall. The ball's initial momentum is equal to its mass times its velocity, and its final momentum is zero since it comes to a stop after hitting the wall. The change in momentum is equal to the final momentum minus the initial momentum, which is equal to the negative of the initial momentum. Since the ball has a mass of 5.0 kg and a velocity of 2 m/s, its initial momentum is 5.0 kg * 2 m/s = 10.0 kg m/s. Therefore, the change in momentum is -10.0 kg m/s and the magnitude of the resulting impulse is 10.0 kg m/s, which is equal to 10.0 Ns. So, the correct answer is 10.0kgms−1.

Lee la nota de la lección en Newton’s Laws Of Motion (WAEC)

Lee la nota de la lección en Work, Energy And Power (WAEC)

Lee la nota de la lección en Equilibrium Of Forces (WAEC)

Newton’s Laws Of Motion

Work, Energy And Power

Equilibrium Of Forces

Ver respuesta

Pregunta 33 Informe

A man walks 1km due east and then 1 km due north. His displacement is

√2km N 45°E

1km N 30°E

1km N 15°E

√2km N 60°E

Detalles de la respuesta

The man first walks 1 km due east, which means he has moved 1 km horizontally to the right of his starting point. Then, he walks 1 km due north, which means he has moved 1 km vertically upwards from his previous position. To find his displacement, we need to draw a straight line from his starting point to his final position, which represents the shortest distance between the two points. This line is called the displacement vector. We can use the Pythagorean theorem to calculate the length of the displacement vector. The horizontal and vertical distances are the two legs of a right-angled triangle, and the hypotenuse is the length of the displacement vector. Using the Pythagorean theorem, we get: displacement = √((1 km)^2 + (1 km)^2) = √2 km The direction of the displacement vector is the angle between the displacement vector and the due north direction. We can find this angle using trigonometry. The tangent of the angle is the ratio of the horizontal distance to the vertical distance: tan(θ) = (1 km) / (1 km) = 1 Using a calculator, we can find that the angle is 45°. Therefore, the man's displacement is √2 km in the direction N 45° E. So, the correct answer is √2km N 45°E.

Lee la nota de la lección en Scalars And Vectors (JAMB)

Lee la nota de la lección en Position, Distance And Displacement (WAEC)

Scalars And Vectors

Position, Distance And Displacement

Ver respuesta

Pregunta 34 Informe

An object weighs 30N in air and 21N in water. The weight of the object when completely immersed in a liquid of relative density 1.4 is

25.2N

17.4N

12.6N

9.0N

Detalles de la respuesta

Weight of water displaced = upthrust = 30 - 21 = 9N
Mass of water displaced = $\frac{9}{10}$ = 0.9kg
Volume of object = 9 × 10 $^{- 4}$ m $^{3}$
= (9 × 10 $^{- 4}$ ) (1.4 ×103)

= 1.26kg = 12N
30 - 12.6 = 17.4N

Lee la nota de la lección en Gravitational Field (JAMB)

Gravitational Field

Ver respuesta

Pregunta 35 Informe

A solid cube of side 50cm and mass 75kg floats in a liquid with $ \frac{1}{3} $ of its height above the liquid surface. The relative density of the liquid is?

0.33

0.50

0.67

0.90

Detalles de la respuesta

Volume of liquid displaced
=

\frac{2}{3}

(0.5)

^{3}

Mass of liquid displaced = mass of floating cube = 75kg
Density of liquid =

\frac{m a s s}{v o l u m e}

=

\frac{75}{(\frac{7}{3 (0.5)})}

× 3
= 0.9 × 103kgm

^{- 3}

R.D of liquid =

\frac{(0.9)}{(1.0)}

× 103
= 0.9

Ver respuesta

Pregunta 36 Informe

In a series R-L-C circuit at resonance, the voltages across the resistor and the inductor are 30V and 40V respectively. What is the voltage across the capacitor?

30V

70V

50V

40V

Ver respuesta

Pregunta 37 Informe

The linear expansivity of brass is $2 \times 10^{-5}\,\text{C}^{-1}$. If the volume of a piece of brass is 15.00cm at 0°C, what is the volume at 100°C

16.03cm

^{3}

15.09cm

^{3}

16.00cm

^{3}

15.03cm

^{3}

Detalles de la respuesta

The linear expansivity of brass is given as 2 x 10^-5 /°C. This means that for every 1°C increase in temperature, the brass expands by 2 x 10^-5 of its original size. To find the new volume of the brass at 100°C, we need to take into account the expansion in all three dimensions (length, width, and height). Since the expansivity given is for length only, we need to find the expansivity in all three dimensions by multiplying it by 3. The expansivity in all three dimensions is: 3 x (2 x 10^-5 /°C) = 6 x 10^-5 /°C To find the new volume, we can use the formula: Vf = Vi (1 + αΔT) where Vf is the final volume, Vi is the initial volume, α is the expansivity in all three dimensions, and ΔT is the change in temperature. Plugging in the values, we get: Vf = 15.00 cm3 (1 + (6 x 10^-5 /°C) x (100°C - 0°C)) Vf = 15.09 cm3 Therefore, the volume of the brass at 100°C is 15.09 cm3.

Lee la nota de la lección en Thermal Expansion (JAMB)

Thermal Expansion

Ver respuesta

Pregunta 38 Informe

When an atom loses or gain a charge it becomes

An electron

An ion

A neutron

A proton

Detalles de la respuesta

When an atom loses or gains a charge, it becomes an ion. An ion is a type of atom that has an unequal number of protons and electrons, giving it a net electrical charge. If an atom loses one or more electrons, it becomes positively charged and is called a cation. On the other hand, if an atom gains one or more electrons, it becomes negatively charged and is called an anion. So, in summary, an atom can lose or gain electrons to become an ion, which has a net electrical charge.

Lee la nota de la lección en Electrostatics (JAMB)

Electrostatics

Ver respuesta

Pregunta 39 Informe

Which of the following concepts is not an evidence of the particles nature of matter?

Diffusion

Brownian motion

Diffraction

Crystallization

Detalles de la respuesta

The particle nature of matter refers to the idea that matter is made up of tiny particles that are constantly moving. Diffusion, Brownian motion, and crystallization are all examples of phenomena that can be explained by the particle nature of matter. However, diffraction is not an evidence of the particle nature of matter. Diffraction is a phenomenon that occurs when waves encounter an obstacle or a slit, causing them to spread out and interfere with each other. While particles can also exhibit diffraction, this is a property of waves and is not specific to particles. In summary, diffusion, Brownian motion, and crystallization are all evidences of the particle nature of matter, but diffraction is not.

Lee la nota de la lección en Thermal Expansion (JAMB)

Thermal Expansion

Ver respuesta

Pregunta 40 Informe

The inner diameter of a small test tube can be measured accurately using a

Micrometres screw gauge

Pair of dividers

Metre rule

Pair of vernier calliper

Detalles de la respuesta

A vernier caliper is a measuring device used to precisely measure linear dimensions. It is a very useful tool to use when measuring the diameter of a round objects like cylinders because the measuring jaws can be secured on either side of the circumference.
Vernier calipers have both a fixed main scale and a moving vernier scale. The main scale is graduated in either millimetres or tenths of an inch. The vernier scale allows much more precise readings to be taken (usually to the nearest 0.02mm or 0.001 inch) in comparison to a standard ruler (which only measures to th nearest 1mm or 0.25 inch).
The vernier scale was invented by French mathematician Pierre Vernier in 1631. As part of the vernier caliper, it is used together with the main scale, and helps to provide very precise measurements. Vernier calipers usually show either imperial or metric measurements, but some measure in both.

Lee la nota de la lección en Temperature And Its Measurement (JAMB)

Lee la nota de la lección en Measurements And Units (JAMB)

Temperature And Its Measurement

Measurements And Units

Ver respuesta






Mantén pulsado para arrastrar.
Haz clic aquí para cerrar