JAMB UTME - Physics - 2015

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Transformers are electrical devices that are used to transfer electrical energy from one circuit to another through electromagnetic induction. One of the challenges with transformers is that they can experience energy losses, which can reduce their efficiency. To address this issue, several steps can be taken: I. Using a soft iron core: Soft iron is a type of metal that has low magnetic hysteresis, which means it can be magnetized and demagnetized quickly and easily. This makes it an ideal material for transformer cores because it can store and release energy efficiently. II. Laminating the iron core: Eddy currents are electrical currents that can be induced in conductive materials, like transformer cores, when they are exposed to changing magnetic fields. These eddy currents can cause energy losses through heat generation. Laminating the iron core with thin layers of insulating material, like paper or plastic, can reduce the flow of eddy currents and therefore reduce energy losses. III. Designing an efficient iron core: The shape and size of the iron core can also impact energy losses in a transformer. A well-designed iron core can reduce the distance that magnetic fields have to travel, which can reduce energy losses. Based on this explanation, the answer would be: I, II, & III only.

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A body floats in fluid when it displaces its own weight of the fluid. This is known as Archimedes' principle. When an object is placed in a fluid, it experiences an upward force called buoyancy. This buoyant force is equal to the weight of the fluid displaced by the object. If the buoyant force is greater than the weight of the object, the object will float. If the buoyant force is less than the weight of the object, the object will sink. According to Archimedes' principle, an object floats in a fluid when it displaces its own weight of the fluid. This means that the weight of the fluid displaced by the object is equal to the weight of the object. So, the buoyant force acting on the object is equal to its weight, and the object floats in equilibrium. Therefore, the correct option is: - Displaces its own mass of the fluid is not correct because an object displaces its own volume of the fluid, but the weight of the fluid displaced is equal to the weight of the object, not its volume. is not correct because the object does not displace its own density of the fluid. is not correct because the object is still subjected to gravity, but the buoyant force acting on it counteracts the gravitational force and allows it to float.

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The frequency of the X-rays emitted by the radioactive source can be calculated using the formula: frequency = speed of light / wavelength The speed of light is approximately 3 x 10^8 m/s. Substituting the given wavelength of 10^-13 m into the formula, we get: frequency = 3 x 10^8 / (10^-13) = 3 x 10^21 Hz Therefore, the frequency of the X-rays emitted by the radioactive source is 3 x 10^21 Hz. Option C, which states 3 x 10^21 Hz, is the correct answer. Option A, B, and D are incorrect because they do not match the calculated frequency.

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The general gas law can be written as PV ÷ T = a constant. The general gas law, also known as the combined gas law, relates the pressure (P), volume (V), and temperature (T) of a gas. It states that the product of the pressure and volume of a gas divided by its temperature is a constant value. Mathematically, this is expressed as PV ÷ T = a constant. This means that if you increase the pressure of a gas while keeping the temperature and volume constant, the volume will decrease. Similarly, if you increase the temperature of a gas while keeping the pressure and volume constant, the volume will increase. The general gas law is a very useful tool for understanding the behavior of gases and predicting how they will behave under different conditions.

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For maximum range (Rmax)

Rmax = U2 ÷ α g where Rmax = 36m, U2 = ?, g = 9.8m/s2

36 = U2 ÷ 2 × 8.8

U2 = 36 × 2 × 9.8m = 705.8

√U = √ 705.6 = 26.5 (squaring both side)

u= 26.5m/s, U = 27m/s (Approx.)

The speed of projection = 27m/s2

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Mechanical advantage (M.A) of a machine is the ratio of its load to effort

Mathematically

Mechanical advantage (M.A) = Load (L) ÷ Effort (E)

In symbol M.A = L/E

Note:Mechanical (advantages has no S.I unit)

If M.A = 4 then,

L/E = 4/1

The ratio of load to effort = 4 : 1 respectively

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Assuming that air resistance is neglected, both the light and heavy objects will fall at the same rate and reach the ground at the same time. This is known as the principle of equivalence and is a fundamental principle of physics. According to this principle, the acceleration due to gravity is the same for all objects, regardless of their mass. This means that both the light and heavy objects will experience the same acceleration as they fall towards the ground. The acceleration due to gravity near the surface of the Earth is approximately 9.8 m/s^2. This means that an object in free fall near the surface of the Earth will accelerate at a rate of 9.8 m/s^2. As a result, both the light and heavy objects will fall at the same rate and reach the ground at the same time. Therefore, the answer to the question is Both light and heavy subject reach the ground at the same time.

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The period of an alternating current (AC) is the time it takes for one complete cycle of the current. In other words, it is the time taken for the current to change direction and then return to its original direction. The period is usually measured in seconds. The frequency of an AC is the number of complete cycles of the current that occur per second. The unit of frequency is Hertz (Hz), which means cycles per second. The relationship between frequency and period can be expressed by the formula: Period (in seconds) = 1 / Frequency (in Hertz) If an alternating current has a frequency of 100 Hz, we can use the above formula to find its period as follows: Period = 1 / 100 = 0.01 seconds Therefore, the period of an alternating current with a frequency of 100 Hz is 0.01 seconds. So, the answer is 0.01sec.

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The correct answer is "Magnetic relay device". A magnetic relay is an electrical switch that is activated by a magnetic field. It's used to control a high-power or dangerous circuit using a low-power circuit. For example, you can use a low-power circuit to turn on a high-power circuit, such as turning on a large electrical motor. The low-power circuit creates a magnetic field that activates the magnetic relay, which then switches on the high-power circuit. This allows you to control the high-power circuit from a safe distance and protect yourself from potential electrical hazards.

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The correct option is "J.J Thompson." J.J. Thompson, a British physicist, discovered electrons in 1897. He conducted experiments with cathode ray tubes and observed that they produced a beam of negatively charged particles, which he called electrons. Thompson's discovery of electrons paved the way for further research into atomic structure and the development of modern electronics. The other options are not correct because they did not discover electrons. James Chadwick is known for discovering the neutron, Sir Isaac Newton is famous for his contributions to the fields of physics and mathematics, but he did not discover electrons, and there is no historical figure named Charles Newton who is associated with the discovery of electrons.

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As object and image are usually at equal distance apart from the mirror

Distance between Abioye (a) and hip image (I) = AI

i.e. AI = 4.7 + 47 = 9.4m

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The correct option is "3 only". When an object falls freely towards the ground, it experiences a gravitational force that accelerates it downwards. This force does work on the object, converting its potential energy into kinetic energy as it gains speed. At the same time, the object loses potential energy as it moves closer to the ground. According to the law of conservation of energy, the total energy of a closed system remains constant. In this case, the object-earth system is the closed system, and there are only two types of energy present: potential energy (due to the object's position in the gravitational field) and kinetic energy (due to the object's motion). Therefore, as the object falls freely towards the ground, its potential energy decreases while its kinetic energy increases. However, the sum of the two energies remains constant. This means that is correct. is incorrect because the total energy of the object-earth system is not just kinetic energy. is also incorrect because the ratio of potential energy to kinetic energy is not constant - it changes as the object falls.

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Radio waves belong to the class of wave whose velocity is about 3 × 10^8 m/s. Radio waves are a type of electromagnetic wave, which means they are composed of both electric and magnetic fields that oscillate at right angles to each other and to the direction of wave propagation. Like all electromagnetic waves, radio waves travel at the speed of light in a vacuum, which is approximately 3 × 10^8 m/s. This means that radio waves also travel at this speed in air and other materials, although their speed may be slightly slower in denser materials like water or metal. It's important to note that the velocity of a wave refers to the speed at which the wave propagates through a medium, which is different from the frequency and wavelength of the wave. The frequency of a wave refers to the number of oscillations per unit time, while the wavelength refers to the distance between two successive peaks or troughs of the wave. Radio waves can have a wide range of frequencies and wavelengths, which determine their properties and applications in various fields such as communication, broadcasting, and remote sensing.

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Simple pendulum does not depend on thermal expansion

Five alarms, Thermostat and Bimetallic thermometer are application of thermal expansion of solid

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The gravitational force of attraction between two objects is given by the formula: F = G * (m1 * m2) / r^2 where F is the force of attraction, m1 and m2 are the masses of the two objects, r is the distance between their centers of mass, and G is the gravitational constant, which has a value of 6.67 x 10^-11 Nm^2/kg^2. In this case, we are given the masses of the two planets (10^24 kg and 10^27 kg) and the distance between them (10^20 meters). We can plug these values into the formula to calculate the gravitational force of attraction: F = (6.67 x 10^-11 Nm^2/kg^2) * ((10^24 kg) * (10^27 kg)) / (10^20 meters)^2 F = 6.67 x 10^-11 * 10^51 / 10^40 F = 6.67 x 10^11 N Therefore, the gravitational force of attraction between the two planets is approximately 6.67 x 10^11 N. ("6.67N") is the correct answer. Note: The answer may seem very large, but this is because the masses and distances involved are very large (in astronomical scales).

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d = y, s = 6 m/s (The Man & Plane Mirror)

d – δy, s = (5 &ndash ;6) m/s (The Man and Image)

d2 ÷ s1 = d2 ÷ s2, y ÷ 6 = 2y ÷ s + 6

Y (s + 6) = 2y × 6

s + 6 = 12

So = 12 – 6 = 6

Since S + 6 = 0

Then, S = 6 (substitute the value of S i.e S = 6)

Into S + 6 = 0

∴So = S + 6 = 6 + 6 = 12 m/s

∴ S = 12 m/s

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A lodestone is a natural magnet that points towards the Earth's magnetic North Pole when suspended freely. The Earth has a magnetic field that causes a lodestone to align in a North-seeking direction. When a lodestone is suspended freely, it will align itself in a way that points towards the Earth's magnetic North Pole, which is why a lodestone points towards the North-South direction. So, the correct answer is N – S when suspended freely.

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In an inelastic collision, linear momentum is conserved and energy is decreased

Momentum and kinetic energy are conserved in elastic collision

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The answer is "Magnitude and direction." A vector quantity is a type of physical quantity that has both magnitude (size) and direction. Magnitude refers to the numerical value of the quantity, while direction refers to the path along which the quantity is moving. For example, if we want to describe the velocity of an object, we need to specify both its speed (magnitude) and the direction in which it is moving. Without knowing the direction, we cannot fully understand the velocity of the object. Similarly, for other vector quantities such as force, acceleration, and displacement, both magnitude and direction must be specified to fully describe the quantity.

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Heat transfer by convection is a process in which heat is transferred from one place to another by the movement of a fluid, such as a gas or a liquid. Convection occurs because when a fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks. Of the substances listed, one that can experience convection is water. When water is heated, the warmer water near the heat source becomes less dense and rises, while cooler water sinks to take its place. This creates a circular motion of water, which is known as a convection current. This process can transfer heat from one part of the water to another, and it is used in many applications, such as heating systems, cooking, and cooling systems. On the other hand, stone and wood are poor conductors of heat, which means they do not transfer heat very well. Mercury is a liquid metal that is a good conductor of heat, but it does not experience convection in the same way that water does because it is a metal and its behavior is different from that of liquids. Therefore, the answer to the question is water.

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The approximate peak value of the voltage is "283 volts". The r.m.s (root mean square) value of a supply voltage is a measure of the effective value of the voltage, which is equivalent to the heating effect of the voltage on a resistive load. The peak value of a sinusoidal voltage waveform is equal to the r.m.s value multiplied by the square root of 2 (√2). So, for a 200v r.m.s voltage, the peak value can be calculated as follows: Peak value = 200v × √2 = 200v × 1.414 = 283 volts This means that the maximum value of the voltage waveform is approximately 283 volts. It's important to note that this is just an approximation, and the actual peak value may vary depending on the shape of the voltage waveform.

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Infrared rays can be used to take photographs in the haze. Infrared radiation is a type of electromagnetic radiation with longer wavelengths than visible light. This allows it to penetrate through the haze and produce images that are clearer than those taken with visible light. Infrared photography is commonly used in various fields, such as in military and law enforcement to see through the haze, smoke, and other obstructions, as well as in scientific research to study the thermal properties of objects. Radio waves, visible light, and gamma rays are not typically used to take photographs in the haze, as they are not able to penetrate through the haze as effectively as infrared radiation.

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The statement in the question suggests that one of the given options is not a desirable characteristic of a good electric cell. A good electric cell is a device that converts chemical energy into electrical energy through a series of chemical reactions. The cell must have two electrodes, a positive and a negative, and an electrolyte that can conduct ions between the electrodes. The first option, "A minimum of polarization effect", is a desirable characteristic of a good electric cell. Polarization occurs when the buildup of reaction products at the electrodes causes a decrease in the rate of the chemical reaction, leading to a decrease in the voltage of the cell. A good electric cell should minimize polarization effects to maintain a steady voltage output. The second option, "A long life", is also a desirable characteristic of a good electric cell. A good electric cell should be able to provide a consistent voltage output over an extended period of time without the need for frequent replacement or recharging. The third option, "A cheap and safe electrolyte", is also a desirable characteristic of a good electric cell. The electrolyte should be readily available and inexpensive, and it should not pose a safety hazard to users. The fourth option, "Cost and dangerous of the cell", is not a desirable characteristic of a good electric cell. A good electric cell should not be excessively expensive, and it should not pose a safety risk to users. Therefore, the correct answer is "Cost and dangerous of the cell".

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The correct answer is Compression and Rarefaction. When a longitudinal wave travels through a medium, it causes particles in the medium to oscillate back and forth parallel to the direction of wave propagation. The compressed regions are the areas where the particles are pushed closer together than their normal positions, while the rarefaction regions are the areas where the particles are spread apart more than their normal positions. These compressed and rarefied regions are collectively known as compression and rarefaction, respectively. For example, when sound waves travel through air, the compressed regions correspond to the high-pressure regions (peaks) of the sound wave, while the rarefaction regions correspond to the low-pressure regions (troughs) of the sound wave.

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Volatile liquids usually have low boiling points. Volatility refers to the tendency of a liquid to evaporate quickly and easily into a gas. Liquids with low boiling points are more likely to evaporate and become a gas at room temperature and pressure, which is why they are referred to as volatile liquids. Examples of volatile liquids include gasoline, alcohols, and solvents. These liquids are used in a variety of applications, such as fuel, cleaning agents, and industrial processes. In comparison, liquids with high boiling points have a low volatility and are less likely to evaporate into a gas at room temperature. They are typically used in applications where the liquid needs to be stored for a long period of time without evaporating, such as in cooking and food preparation.

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M= 3kg, r = 0.7m, v = 2m/s

v = wr

w = angular velocity

r = radius in an tangential circular

v = speed of an object

W = V/δ = 2/ 0.7 = 2.85

W = 2.853rads–1 (total interest whole number)

W = &approx.; 3rads–1Angular velocity (w) = 3rads–1

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The optical instrument that is suitable for viewing nearby objects is a microscope. A microscope uses lenses to magnify small objects that are too small to see with the naked eye. It works by gathering and focusing light onto a small object, making it appear much larger. Microscopes are commonly used in scientific research, medicine, and education to examine cells, microorganisms, and other small structures. They come in various types and designs, including compound microscopes, stereo microscopes, and electron microscopes.

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We can use the formula: heat capacity = mass x specific heat capacity to find the mass of the zinc. Rearranging the formula, we get: mass = heat capacity / specific heat capacity Substituting the given values, we get: mass = 40 J/K / 380 J/kg K mass = 0.1053 kg So, the mass of the zinc is approximately 0.11 kg. Therefore, the correct option is: - 0.11kg , 3, and 4 are not correct because they are different values and do not match the result of the calculation.

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Gas thermometers are considered best for use to achieve an accurate temperature than others, such as liquid in glass thermometers such as mercury, clinical and alcohol thermometer

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The correct answer is: Fall freely from the earth’s gravitational field Weightlessness is experienced by the crew member of a spaceship when they are falling freely under the influence of the earth's gravity. In space, the force of gravity is still present, but objects in orbit are constantly falling towards the Earth, which creates the sensation of weightlessness. The spaceship and crew inside are all falling towards the Earth together, but because they are also moving horizontally at a high enough speed, they never actually hit the Earth. This constant state of freefall creates the feeling of weightlessness that astronauts experience in space.

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General formular of Gas laws

(P1V1) ÷ T1= (P2V2) ÷ T2

P1 = 800mmHg, V, = 76cm3, Tr = 273 + 27 = 300k

P2 = 760mmHg, V2 = ? T2= 273 + 0 = 273 + 6 = 277k

(800 × 76) ÷ 300 = (760 × V2) ÷ 273

V2 = (300 × 76 × 273) ÷ (300 × 760) = 72.8 cm3

The volume of gas as S.T.P = 72.8 cm3

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The correct answer is "The sun ray from the sky were passing from a hot air (layer) to cold layer". This is because the motor boy may have seen a mirage, which is a phenomenon where light is bent by the difference in temperature between a hot air layer near the ground and a colder layer of air above it. This bending of light can cause distant objects to appear to shimmer or appear as a pool of water on a hot day. This is a common occurrence in hot, desert regions where the air temperature is much higher near the ground than at higher altitudes.

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A stroboscope is a device that produces flashes of light at regular intervals. By adjusting the frequency of the flashes, it is possible to make a moving object appear stationary or appear to move in slow motion or fast motion. Therefore, the correct option for the question is: - Stationary

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The boiling point of water can increase, if

1. Heating it in a sealed flask

2. The rate of the heat supply is increased

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The S.I unit of relative density is "has no S.I unit." Relative density, also known as specific gravity, is the ratio of the density of a substance to the density of a reference substance, usually water. Since it is a ratio of two quantities with the same unit, it does not have a unit itself. Therefore, relative density has no S.I unit. For example, if the density of a substance is 5 g/cm^3 and the density of water is 1 g/cm^3, then the relative density of the substance is 5/1 = 5. Note that the units of both densities cancel out, leaving a dimensionless quantity. In summary, relative density is a dimensionless quantity, which means it has no S.I unit.

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The symbol -10 X is used to represent electrons. Electrons are negatively charged particles that orbit the nucleus of an atom. The negative charge of an electron is denoted by the symbol -1, and the atomic number of an element represents the number of protons in the nucleus. Therefore, the symbol -10 X represents 10 electrons. It is worth noting that this notation is often used in physics and chemistry to represent the charge and number of electrons in a system. In comparison, protons are positively charged particles found in the nucleus of an atom, and neutrons are neutral particles also found in the nucleus. Atoms are the smallest unit of matter that retains the chemical properties of an element.

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Simple pendulum does not depend on thermal expansion

Five alarms, Thermostat and Bimetallic thermometer are application of thermal expansion of solid

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The magnitude of the couple (torque) that acts on a rotating circular disc can be calculated using the equation: τ = Fr where τ is the torque, F is the force, and r is the radius. In this case, the force is 2 N and the radius is 2 m, so the torque is: τ = F * r = 2 N * 2 m = 4 Nm. So, the magnitude of the couple that acts on the rotating circular disc is 4 Nm.

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Sun are self luminous source
Moon is a non – luminous

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If an object is placed at a height of h above the ground at a stationary point, it possesses potential energy. Potential energy is a type of energy that is stored in an object due to its position or configuration. In this case, the object has the potential to do work by virtue of its position above the ground. The potential energy of an object at a height h above the ground is given by the formula: Potential energy = mgh where m is the mass of the object, g is the acceleration due to gravity, and h is the height of the object above the ground. As the object is at a stationary point and not in motion, it does not possess any kinetic energy. However, it possesses potential energy due to its position above the ground. When the object is allowed to fall to the ground, its potential energy is converted to kinetic energy, and it will be in motion with a velocity that depends on its mass and the height from which it was dropped. In summary, the correct answer to the given question is potential energy.

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To convert Celsius to Kelvin, we add 273.15 to the Celsius temperature. Therefore, to convert 45°C to Kelvin, we simply need to add 273.15 to 45, which gives: 45 + 273.15 = 318.15 Kelvin (rounded to two decimal places) Therefore, the correct answer is: 318K.

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The correct expression of Boyle's law is "P1V1 = P2V2". This law states that the product of the pressure and volume of a gas at a constant temperature is always constant. In other words, if you change the pressure of a gas, its volume will change in an opposite direction so that the product of the pressure and volume remains constant. For example, if you increase the pressure of a gas, its volume will decrease, and vice versa. This relationship between pressure and volume is useful in many real-world applications, such as in the design of gas storage tanks and gas transport pipelines.

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The eyeball is a complex structure that allows us to see. It is made up of several parts, including the cornea, iris, pupil, lens, retina, and optic nerve. The outermost layer of the eyeball is a tough, white, fibrous layer called the sclera, which is also known as the "white of the eye". Option A, which states "Sclerotic", is the correct answer. The sclera is a protective outer layer of the eyeball that provides support and helps maintain the shape of the eye. It is made up of dense connective tissue and is continuous with the clear cornea at the front of the eye. The sclera is important for maintaining the structural integrity of the eye and protecting the delicate inner parts from injury. Option B, Choroid coal, and Option C, Optical fiber, are incorrect answers as they do not correctly identify the outermost layer of the eyeball. Option D, Accommodation, refers to the ability of the lens of the eye to change shape to focus on objects at different distances and is not related to the outer layer of the eyeball.

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Heat can be transferred from one object to another through three different mechanisms: conduction, convection, and radiation. Expansion, on the other hand, is not a mechanism of heat transfer. Conduction is the transfer of heat through a material or between materials in contact. For example, when you touch a hot object, heat is transferred from the object to your hand by conduction. Convection is the transfer of heat by the movement of fluids, such as air or water. This is why a fan blowing air across your skin can make you feel cooler. Radiation is the transfer of heat through electromagnetic waves, such as those emitted by the sun or a fire. This is why you can feel the warmth of a fire even if you are not in direct contact with it. Expansion, on the other hand, refers to the increase in volume of a material due to an increase in temperature. While expansion can be a result of heat transfer, it is not a mechanism of heat transfer itself. Therefore, the answer to the question is Expansion. Heat can be lost to the surrounding through conduction, convection, and radiation, but not through expansion.

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The correct answer is "2 seconds". When an object is dropped from a height, it falls under the influence of gravity, which accelerates it downwards. This acceleration due to gravity is denoted by 'g' and has a value of approximately 10 m/s^2 on the surface of the Earth. To determine how long it takes for the ball to reach the ground, we can use the following kinematic equation: d = (1/2) * g * t^2 where 'd' is the distance traveled, 'g' is the acceleration due to gravity, and 't' is the time taken. In this case, the initial height of the ball is 20 m, so we can set 'd' equal to 20 m. We know that 'g' is 10 m/s^2, so we can substitute these values into the equation to get: 20 = (1/2) * 10 * t^2 Simplifying this equation, we get: t^2 = 4 Taking the square root of both sides, we get: t = 2 Therefore, it takes 2 seconds for the ball to reach the ground. So, the correct option is "2 sec".

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The time it takes for an object to fall from a certain height can be calculated using the equation t = sqrt(2h/g), where h is the height and g is the acceleration due to gravity. In this case, the mango was dropped from a height of 50 meters and g is given as 10m/s^2. Plugging these values into the equation, we get: t = sqrt(2 x 50/10) = sqrt(10) = 3.2 sec Therefore, the mango takes 3.2 seconds to reach the ground. So the correct option is: 3.2sec.

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Velocity Ratio (V.R) = distance moved by the effort (x)÷ distance moved by the load (y)

i.e. V.R = x/y

v. R = 5, x/y = ?

i.e x/y = 5/1; , where x = 5, y = 1

x : y = 5 : 1

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Work (w) = Force (f) × Distance (d)

Note: f = ma = mass × acceleration

= mass ×acceleration ×distance

= kg ×ms–2 × m

= kg m2 5–2

(Note: the dimension of kg = M, M = L & S = T)

Work = ML2 T–2 = Ma Lb Tc

i.e. Ma Lb Tc = as 1, b = 2, c = –2

The value of a, band c = 1, 2, –2

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The answer is "Gas thermometer." A gas thermometer is the best option for achieving the most accurate temperature measurements. This is because gas thermometers have a very high degree of sensitivity and precision, and they can measure temperatures to a very fine degree of accuracy. Gas thermometers work by using a gas (usually hydrogen or helium) as the temperature-sensitive material. As the gas is heated or cooled, its volume changes, and this change in volume is used to calculate the temperature. Gas thermometers are often used as the standard for calibrating other temperature measurement devices. Mercury and alcohol thermometers are less accurate than gas thermometers, although they are still widely used in many applications. Clinical thermometers are specialized thermometers used for measuring human body temperature, and they are typically less precise than other types of thermometers. In summary, while all of the thermometers listed can be used for temperature measurements, a gas thermometer is the best option for achieving the most accurate and precise results.

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To calculate the inductance (L) of an inductor, we need to use the formula: XL = 2πfL Where XL is the reactance of the inductor, f is the frequency in hertz, and L is the inductance in henrys. In this question, we are given that the reactance of the inductor is 1 at 50 Hz. We can substitute these values into the formula and solve for L: 1 = 2π x 50 x L L = 1 / (2π x 50) L ≈ 0.00318 henrys (rounded to five decimal places) Therefore, the correct answer is: 0.01H, which is the same as 0.00318 henrys when rounded to two decimal places.