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- You are provided with a 12V a.c. source, four diodes and a resistor.
(i) Draw a circuit diagram for full wave rectifier and show the points...(Solved)
You are provided with a 12V a.c. source, four diodes and a resistor.
(i) Draw a circuit diagram for full wave rectifier and show the points at which the output is taken.
(ii) Sketch a graph of voltage against time before rectification.
(iii) Sketch a voltage – time graph after rectification.
(iv) Sketch a voltage – time graph after rectification with a capacitor connected across the resistor in (i)
Date posted: September 9, 2019. Answers (1)
- The figure below shows a system of capacitors connected to 100V supply.(Solved)
The figure below shows a system of capacitors connected to 100V supply.
(i) the value of a capacitor for the whole circuit system.
(ii) the charge through the 6µF capacitor.
(iii) the p.d across of the 8µF capacitor.
Date posted: September 9, 2019. Answers (1)
- Draw the electric field pattern in the figure below.(Solved)
Draw the electric field pattern in the figure below.
Date posted: September 9, 2019. Answers (1)
- A transformer supplies 12V when it is connected to 240V supply of electricity. The output of the transformer is connected to 12V 36W bulb. The...(Solved)
A transformer supplies 12V when it is connected to 240V supply of electricity. The output of the transformer is connected to 12V 36W bulb. The current drawn from the supply by the transformer is 0.5A. Calculate:
(i) the input power of the transformer.
(ii) the current drawn from the transformer.
(iii) The output power of the transformer.
(iv) the efficiency of the transformer
Date posted: September 9, 2019. Answers (1)
- The two free ends of a coil are connected to a center – zero galvanometer. When the north pole of magnet is moved towards the...(Solved)
The two free ends of a coil are connected to a center – zero galvanometer. When the north pole of magnet is moved towards the coil, the pointer deflects in the direction shown in the figure below.
State with a reason the behaviour of the pointer inn the following cases:
(i) The north pole of the magnet is held stationary near P.
(ii) The north pole of the magnet is made to approach the coil from end Q
Date posted: September 9, 2019. Answers (1)
- The figure below represents a displacement – time graph for a wave.Determine the frequency of the wave.(Solved)
The figure below represents a displacement – time graph for a wave.Determine the frequency of the wave.
Date posted: September 9, 2019. Answers (1)
- A ray of light makes an angle of 350 with the glass surface. Calculate the total distance the ray covers through a glass of refractive...(Solved)
A ray of light makes an angle of 350 with the glass surface. Calculate the total distance the ray covers through a glass of refractive index 1.45, given that the width of the glass is 6cm
Date posted: September 9, 2019. Answers (1)
- Complete the following table(Solved)
Complete the following table
Date posted: September 9, 2019. Answers (1)
- 200g of ice at 00C is added to 400g water in a well lagged calorimeter of mass 40g. The initial temperature of the water was...(Solved)
200g of ice at 00C is added to 400g water in a well lagged calorimeter of mass 40g. The initial temperature of the water was 400C. If the final temperature of the mixture is X0C, (Specific latent of fusion of ice L = 3.36 x 105JK/g, specific heat capacity of water, c = 4200J/kg/K, specific heat capacity of copper = 400J/kg/K)
(i) Derive an expression for the amount of heat gained by ice to melt it and raise its temperature to X0C
(ii) Derive an expression for the amount of heat lost by the calorimeter and its content when their temperature falls to X0C.
(iii) Determine the value of X.
Date posted: September 9, 2019. Answers (1)
- Given the following. A filter funnel, a thermometer, a stop watch, ice at 00C, an immersion heater rated P watts, a beaker, a stand, boss...(Solved)
Given the following. A filter funnel, a thermometer, a stop watch, ice at 00C, an immersion heater rated P watts, a beaker, a stand, boss and clamp and weighing machine.Describe an experiment to determine the specific latent heat of fusion of ice. Clearly state the measurements to be made.
Date posted: September 9, 2019. Answers (1)
- The figure below shows dots which were made by a ticker timer – tape attached to a trolley. The trolley was moving in the direction...(Solved)
The figure below shows dots which were made by a ticker timer – tape attached to a trolley. The trolley was moving in the direction shown.
If the frequency used was 60Hz, distance AB = 12cm and BC = 7.2cm, determine
(i) The velocities between AB and BC
(ii) The acceleration of the trolley.
(b) An object is projected horizontally with a velocity of 40m/s at the top of a cliff 100m from the ground. (Take g = 10m/s2)
(i) Calculate the time taken for the object to hit the ground.
(ii) What is the range of the object from the foot of the cliff
Date posted: September 9, 2019. Answers (1)
- Sketch a block and tackle pulley with three movable pulleys in the lower block and two fixed pulleys in the upper block,to give a velocity...(Solved)
Sketch a block and tackle pulley with three movable pulleys in the lower block and two fixed pulleys in the upper block,to give a velocity ratio of 6.
Find:
(i) An effort of 450N is used to raise a load of 2700N. Determine:
- Mechanical advantage (M.A)
- Efficiency of the pulley system.
(ii) If all the wasted energy is used to raise the lower block and the frictional force between pulleys and moving parts is 3.6N; determine the weight of the lower block.
(iii) If the load moved through a distance of 50cm, determine the useful work done by the effort.
Date posted: September 9, 2019. Answers (1)
- The figure below shows a cuboid in two positions. Explain how the stability of the cuboid changes when it is changed from position a to...(Solved)
The figure below shows a cuboid in two positions. Explain how the stability of the cuboid changes when it is changed from position a to b.
Date posted: September 9, 2019. Answers (1)
- The spiral springs shown in the figure below are identical. Each spring has a spring constant K = 200 N/m. Each rod weighs 0.1 N...(Solved)
The spiral springs shown in the figure below are identical. Each spring has a spring constant K = 200 N/m. Each rod weighs 0.1 N and each spring weigh 0.1 N. Determine the total extension caused by the 150 N weight.
Date posted: September 9, 2019. Answers (1)
- A balloon with argon gas of volume 199cm3 at the earth‘s surface where the temperature is 210C, and the pressure 760mm of mercury. If it...(Solved)
A balloon with argon gas of volume 199cm3 at the earth‘s surface where the temperature is 210C, and the pressure 760mm of mercury. If it is allowed to ascend to a height where the temperature is 20C and the pressure 100mm of mercury, calculate the volume of the balloon.
Date posted: September 9, 2019. Answers (1)
- In a faulty mercury-in-glass thermometer it was found that the mercury level stands at 2 cm mark in the tube at 00C and 20cm when...(Solved)
In a faulty mercury-in-glass thermometer it was found that the mercury level stands at 2 cm mark in the tube at 00C and 20cm when in steam above boiling point of water at normal atmospheric pressure. Calculate the temperature when the mercury stands at 13cm mark.
Date posted: September 9, 2019. Answers (1)
- A man whose mass is 80kg stands on weighing machine. When the lift ascends with an acceleration of 2.45m/s2, what is the reading on the...(Solved)
A man whose mass is 80kg stands on weighing machine. When the lift ascends with an acceleration of 2.45m/s2, what is the reading on the scale?
Date posted: September 9, 2019. Answers (1)
- A micrometer screw gauge which had an error of +0.02mm was used to measure the diameter of a spherical marble. If the actual diameter was...(Solved)
A micrometer screw gauge which had an error of +0.02mm was used to measure the diameter of a spherical marble. If the actual diameter was 3.67mm, draw a micrometer screw gauge showing its reading.
Date posted: September 9, 2019. Answers (1)
- State the name of the instrument used to take the following readings;
(i) 10 kg
(ii) 0.00245m(Solved)
State the name of the instrument used to take the following readings;
(i) 10 kg
(ii) 0.00245m
Date posted: September 9, 2019. Answers (1)
- The figure below shows a pair of parallel plates of capacitors connected to a battery. The upper plate is displaced slightly to the left.(Solved)
The figure below shows a pair of parallel plates of capacitors connected to a battery. The upper plate is displaced slightly to the left.
Suggest two adjustments that can be made so as to reduce the effective capacitance.
Date posted: September 9, 2019. Answers (1)