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**Question 1**
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The diagram above is an illustration of an a.c. circuit.Calculate the reactance of the capacitor.

**Question 2**
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The inductive reactance in a circuit of frequency 100Hz is 1ohms. Calculate the inductance of the inductor[π = 3.14]

**Answer Details**

The inductive reactance (X_{L}) in a circuit can be calculated using the formula X_{L} = 2πfL, where f is the frequency of the circuit and L is the inductance of the inductor. Given that X_{L} = 1Ω and f = 100Hz, we can use this formula to calculate the inductance L: X_{L} = 2πfL 1Ω = 2π * 100Hz * L L = 1Ω / (2π * 100Hz) L = 1.59 x 10^{-3}H So, the inductance of the inductor is 1.59 x 10^{-3} H.

**Question 3**
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A note produced by an instrument is distinguished from a similar note produced by another instrument by the?

**Question 4**
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Which of the arrangements of radiations below shows decreasing order of wavelengths?

**Question 5**
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Which of the following statements about distance and displacement is not correct?

**Question 6**
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A ball is swung in a horizontal circle of centre O with a constant speed. acceleration?

**Answer Details**

When a ball is swung in a horizontal circle with a constant speed, it experiences a centripetal acceleration directed towards the center of the circle. The centripetal acceleration is the acceleration required to keep an object moving in a circular path, and it is given by the formula: a = v\(^{2}\) / r where v is the speed of the ball and r is the radius of the circle. In this case, the ball is moving in a horizontal circle, so the centripetal acceleration acts vertically towards the center of the circle (O). So, the acceleration of the ball is toward the center O.

**Question 7**
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In the diagram above, a bulb is lit by drawing 2.0A from 440V a.c. source. Calculate the cost of keeping the bulb on for two days at $0.40 per kilowatt-hour .

**Answer Details**

To solve this problem, we need to use the formula for electrical energy: Energy = Power x Time where Power = Voltage x Current, and Time is in hours. First, we need to find the power of the bulb. Power = Voltage x Current = 440V x 2.0A = 880W. Since we want to find the cost of keeping the bulb on for two days, which is 48 hours, we can now find the energy used by the bulb: Energy = Power x Time = 880W x 48 hours = 42,240 Wh To convert watt-hours (Wh) to kilowatt-hours (kWh), we need to divide by 1000: 42,240 Wh ÷ 1000 = 42.24 kWh Finally, to find the cost of using 42.24 kWh at a rate of $0.40 per kWh, we multiply the two values: 42.24 kWh x $0.40/kWh = $16.90 Therefore, the answer is $16.90.

**Question 8**
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An electric pressing iron is connected to the mains using an insulated wire. wire becomes very hot.

The heat generated in the wire can be minimized by replacing the wire with one of?

**Answer Details**

When an electric current flows through a wire, the wire heats up due to the resistance it offers to the flow of electrons. This heat can be dissipated to the surroundings by conduction, convection, and radiation. The amount of heat generated in the wire depends on the resistance of the wire, the current flowing through it, and the time it takes to flow. To minimize the heat generated in the wire, we need to reduce its resistance. The resistance of a wire depends on its length, cross-sectional area, and the resistivity of the material. Among the options given, the most effective way to minimize the heat generated in the wire is to increase the diameter of the wire. This is because the resistance of a wire is inversely proportional to its cross-sectional area. Therefore, a wire with a greater diameter will have less resistance and hence generate less heat than a wire with a smaller diameter. Thicker insulation will not help much in reducing the heat generated in the wire because insulation is used to prevent the electric current from flowing out of the wire, and it does not affect the flow of current in the wire itself. Thinner insulation or smaller diameter wire may even increase the heat generated because it will lead to a higher resistance and hence more heat generation. Therefore, the correct answer is "greater diameter" because it will reduce the resistance of the wire and hence minimize the heat generated in it.

**Question 9**
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Which of the following statements is an effect of compressing gas molecules at constant temperature?

**Answer Details**

When gas molecules are compressed at constant temperature, the space they occupy decreases, resulting in more molecules per unit volume. As a result, the molecules make more impact per second on the walls of the container, causing an increase in pressure. Therefore, the correct option is: "The molecules make more impact per second on the walls of the container."

**Question 10**
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A rotating disc contains a set of holes in a circle. An air jet is directed onto the holes and a note of frequency 480 Hz is produced. If the number of holes is 20, calculate the speed of rotation of the disc.

**Answer Details**

When the air jet is directed onto the holes in the rotating disc, it causes the air to vibrate at a certain frequency, producing a sound wave. The frequency of the sound wave is determined by the number of holes on the disc and the speed of rotation of the disc. In this case, the note produced has a frequency of 480 Hz and there are 20 holes on the disc. This means that as each hole passes the air jet, it produces a sound wave of 480 Hz. Since there are 20 holes, the disc must rotate 20 times to produce 20 sound waves, which is equivalent to one cycle of the note. Therefore, the speed of rotation of the disc can be calculated by multiplying the frequency of the note by the number of holes and dividing by the number of cycles per second. In this case, we have: Speed of rotation = (480 Hz x 20 holes) / 1 cycle per second Speed of rotation = 9,600 revolutions per second However, the answer choices are given in revolutions per second (rev/s), so we need to convert the speed of rotation to rev/s by dividing by the number of holes: Speed of rotation = 9,600 / 20 Speed of rotation = 480 rev/s Therefore, the correct answer is 24 rev/s.

**Question 11**
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Formation of hydrogen bubbles at the copper plate of a primary cell is called?

**Question 12**
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A current of 2A passes through a wire of resistance 4Ω for 3 minutes. Calculate the energy lost.

**Question 13**
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Which of the following units is equivalent to the unit of electric current?

**Question 14**
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A radioactive material has a half-life of 1.0 hour If 200.0 g of it was present at 6 a.m. on a certain day, how many grams will have decayed by 9 a.m. on the same day?

**Question 15**
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Which of the following scientist suggested that moving particles exhibit wave properties?

**Answer Details**

The scientist who suggested that moving particles exhibit wave properties was Louis de Broglie. De Broglie was a French physicist who developed the theory of wave-particle duality. In his theory, de Broglie proposed that all particles, not just light, have wave-like properties, and that their wavelength is directly proportional to their momentum. This idea challenged the prevailing view of the time, which held that particles and waves were distinct entities, and helped to lay the foundation for the development of quantum mechanics. So, Louis de Broglie is the scientist who suggested that moving particles exhibit wave properties.

**Question 16**
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Which of the following quantities is not an example of force?

**Answer Details**

Out of the given options, mass is not an example of force. Mass is a measure of the amount of matter in an object and is typically measured in kilograms (kg). Force, on the other hand, is a quantity that describes the interaction between two objects and can cause a change in motion or deformation of an object. Tension, weight, and friction are all examples of forces. Tension is the force transmitted through a string, cable, or rope when it is pulled tight. Weight is the force exerted by gravity on an object with mass, and it is measured in Newtons (N). Friction is the force that opposes motion between two surfaces that are in contact with each other. To summarize, mass is not a force, whereas tension, weight, and friction are all examples of forces.

**Question 17**
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A wire of cross-sectional area 2π * 10\(^-{8}\) m\(2\) and resistivity 1.1 x 10\(^-{8}\) Ω m, has a resistance of 21Ω.

Calculate the length of the wire. [π=22/7]

**Answer Details**

The resistance of a wire can be calculated using the formula: R = ρ * L / A where R is the resistance of the wire, ρ is the resistivity of the material, L is the length of the wire, and A is the cross-sectional area of the wire. Given the resistivity of the wire (1.1 x 10\(^-{8}\) Ω m) and its resistance (21 Ω), we can calculate the length of the wire as follows: L = R * A / ρ = 21 Ω * (2 * π * 10\(^-{8}\) m\(^{2}\)) / (1.1 x 10\(^-{8}\) Ω m) = 2 * π * 21 / 1.1 = 120 m So, the length of the wire is 120 m.

**Question 18**
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Which of the following set of quantities have members which are all vectors?

**Answer Details**

The set of quantities that have members which are all vectors is "Force, displacement and momentum." A vector is a quantity that has both magnitude and direction. Force, displacement, and momentum all have both magnitude and direction, making them vector quantities. Pressure, energy, distance, acceleration, work, density, volume, and weight are not all vectors because they do not have both magnitude and direction.

**Question 19**
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The diagram illustrates the velocity- time graph of a body. Calculate the distance covered by the body during the motion

**Question 20**
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The electrons in a cathode-ray tube are produced by?

**Answer Details**

The electrons in a cathode-ray tube are produced by heating a metal filament. This process is called thermionic emission, which means that when a metal filament is heated, the electrons gain enough energy to escape from the surface of the metal and become free electrons. These free electrons are then accelerated towards the anode (positively charged plate) by applying an electric field to the x-plates, and they pass through a small hole in the anode, creating a narrow beam of electrons. This beam of electrons then passes through the tube and is focused by magnetic fields to produce an image on a fluorescent screen.

**Question 21**
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A heat sensitive resistor made of a semiconductor is called?

**Answer Details**

A heat sensitive resistor made of a semiconductor is called a thermistor. A thermistor is a type of resistor whose resistance changes in response to changes in temperature. They are used in a variety of applications, such as temperature sensing and control, temperature compensation, and over-temperature protection. They work by exploiting the property of certain materials to change their electrical resistance in response to changes in temperature. When the temperature of a thermistor increases, its resistance decreases, and when the temperature decreases, its resistance increases. This relationship can be used to measure temperature with high accuracy.

**Question 22**
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A stone is thrown horizontally with initial velocity 15m/s from a tower 20 m high. How long does it take to reach the ground? [g= 10m/s\(^2\)

**Question 23**
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An ice cube has mass of 20 g at 5°C. Calculate the energy required to raise its temperature to 0°C. [Specific heat capacity of ice = 2.1 J/g°c]

**Answer Details**

To calculate the energy required to raise the temperature of an ice cube from 5°C to 0°C, we need to use the specific heat capacity of ice, which is 2.1 J/g°C. The formula for calculating the energy required to change the temperature of a substance is: Energy = mass x specific heat capacity x change in temperature We are given that the mass of the ice cube is 20 g, and we want to raise its temperature by 5°C (from 5°C to 0°C). Plugging in the values into the formula, we get: Energy = 20 g x 2.1 J/g°C x 5°C Simplifying the equation, we get: Energy = 210 J Therefore, the energy required to raise the temperature of the ice cube from 5°C to 0°C is 210 J. The correct option is 4) 210 J.

**Question 24**
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Opening in the eye through which light passes to the retina is called the?

**Answer Details**

The opening in the eye through which light passes to the retina is called the "pupil". The pupil is a small, round hole located in the center of the iris (the colored part of the eye), which regulates the amount of light that enters the eye. The size of the pupil can change depending on the amount of light available and the focus required for near or far vision. The light that enters the eye through the pupil is then focused by the cornea and lens onto the retina at the back of the eye, which sends visual information to the brain through the optic nerve.

**Question 25**
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Which of the following statements about the molecules of solids and liquids is correct? They both

**Answer Details**

The correct option is: "exhibit vibratory motion." The molecules of solids and liquids are constantly in motion, but the type of motion they exhibit differs. In solids, the molecules are packed closely together and vibrate in place. The vibrations are not enough to overcome the attractive forces between the molecules, so the molecules are held in a fixed position. In liquids, the molecules are not as closely packed together as in solids, and they have more freedom of movement. The molecules are in constant motion, but they are still attracted to each other, so they tend to stay close together. The motion of the molecules in liquids is more rapid and random than in solids, but they still exhibit a vibratory motion. Therefore, the statement "They both exhibit vibratory motion" is the correct statement about the molecules of solids and liquids.

**Question 26**
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If the relative humidity of the atmosphere increases, the rate of evaporation of sweat from the human body?

**Answer Details**

If the relative humidity of the atmosphere increases, the rate of evaporation of sweat from the human body decreases. This is because when the relative humidity is high, the air is already saturated with water vapor, and there is less capacity for more water to evaporate into the air. When sweat evaporates, it cools the skin and removes heat from the body. But if the air is already saturated with water vapor, sweat cannot evaporate as effectively, and the body will have a harder time cooling down. Therefore, high humidity can make it feel hotter and more uncomfortable because the body's natural cooling mechanism is less effective.

**Question 27**
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Which of the following actions will increase capacitance of a parallel plate capacitor?

I. Decreasing the distance between the plates

II. Increasing the distance between the plates.

III. Increasing the area of the plates overlap.

IV. Avoiding the use of dielectric between the plate

**Answer Details**

The capacitance of a parallel plate capacitor is defined as the ratio of the charge stored on the plates to the potential difference between the plates. Mathematically, we can express this as: C = Q/V where C is capacitance, Q is charge, and V is potential difference. Now, let's consider each of the options in turn and determine how they affect the capacitance of a parallel plate capacitor. I. Decreasing the distance between the plates When the distance between the plates is decreased, the electric field between the plates increases. This, in turn, increases the charge that can be stored on the plates for a given potential difference. As a result, the capacitance of the capacitor increases. II. Increasing the distance between the plates When the distance between the plates is increased, the electric field between the plates decreases. This, in turn, decreases the charge that can be stored on the plates for a given potential difference. As a result, the capacitance of the capacitor decreases. III. Increasing the area of the plates overlap When the area of the plates overlap is increased, the capacitance of the capacitor increases. This is because there is more surface area for the charges to accumulate on, which increases the amount of charge that can be stored on the plates for a given potential difference. IV. Avoiding the use of dielectric between the plates A dielectric is an insulating material that is placed between the plates of a capacitor to increase its capacitance. Without a dielectric, the capacitance of the capacitor will be smaller. Based on the above analysis, we can see that options I and III will increase the capacitance of a parallel plate capacitor. Option II will decrease capacitance and option IV will not have any effect on capacitance. Therefore, the correct answer is: I and III only.

**Question 28**
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An atom that emits an a-particle?

**Answer Details**

When an atom emits an alpha particle, it may become a different element. An alpha particle is a helium nucleus consisting of two protons and two neutrons. When an atom emits an alpha particle, it loses these two protons and two neutrons and therefore changes its atomic number and becomes a different element. The new element will have an atomic number that is two less than the original element. For example, if an atom of uranium-238 emits an alpha particle, it will become an atom of thorium-234. So, the correct statement is that an atom that emits an alpha particle may become a different element.

**Question 29**
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Which of the following curved surfaces will produce a real image? I. Concave mirror II. Convex mirror III. Diverging lens IV. Converging lens

**Question 30**
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The following statements about a loudspeaker are correct except?

**Question 31**
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Which of the sketched graphs below illustrates the correct variation of the gravitational force, Fg between two objects and the distance, d, between the centres?