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In transmitting power why is it necessary to step up before transmission?. Explain.
(Solved)
In transmitting power why is it necessary to step up before transmission?. Explain.
Date posted:
September 11, 2019
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Answers (1)
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A transformer has 1000 turns in its secondary coil and 10 turns on its primary coil. An alternating current of 2.5A flows in the primary...
(Solved)
A transformer has 1000 turns in its secondary coil and 10 turns on its primary coil. An alternating current of 2.5A flows in the primary circuit when it is connected to a 12V a.c. supply.
(i) State the type of transformer.
(ii) Calculate the power input to the transformer.
(iii) Calculate the e.m.f. across the secondary coil.
(iv) Determine the maximum current that could flow in a circuit connected to the secondary coil if the transformer is 80% efficient. (Use the e.m.f in secondary as calculated in (iii) above).
Date posted:
September 11, 2019
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Answers (1)
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The figure below shows a circuit used to study behavior of diode.
(Solved)
The figure below shows a circuit used to study behavior of diode.
State the behaviour of voltmeter reading as Jockey J is moved from S to R. Explain.
Date posted:
September 11, 2019
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Answers (1)
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The figure below shows a circuit with a coil used to warm oil in a beaker.
(Solved)
The figure below shows a circuit with a coil used to warm oil in a beaker.
(i) Explain how heat is produced in the coil.
(ii) Given that the reading of the ammeter is 2.5A, determine the resistance of the coil.
(iii) How much heat is produced in the coil in a minute?
(iv) Give two changes that can be made in the set-up in order to produce more heat per minute.
Date posted:
September 11, 2019
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Answers (1)
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A policeman standing between two high walls fires a gun. He hears the first echo after 3 seconds and the next 2 seconds later. What...
(Solved)
A policeman standing between two high walls fires a gun. He hears the first echo after 3 seconds and the next 2 seconds later. What is the distance between the wall. (Take velocity of sound = 330m/s).
Date posted:
September 11, 2019
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Answers (1)
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A radioactive sample of half-life 260 days initially has 2.0 x 1020 radioactive atoms. Calculate the number of atoms that would decay after 780 days.
(Solved)
A radioactive sample of half-life 260 days initially has 2.0 x 1020 radioactive atoms. Calculate the number of atoms that would decay after 780 days.
Date posted:
September 11, 2019
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Answers (1)
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Two magnets A and B in the figure below were brought from a point high above a table towards a steel pin.State with a reason...
(Solved)
Two magnets A and B in the figure below were brought from a point high above a table towards a steel pin.
State with a reason which magnet will attract the pin at a bigger height above the table.
Date posted:
September 11, 2019
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Answers (1)
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In a cathode ray oscilloscope the time base is set at 25ms/mm. Given that crest to crest of a signal covers a length of 6cm,...
(Solved)
In a cathode ray oscilloscope the time base is set at 25ms/mm. Given that crest to crest of a signal covers a length of 6cm, determine the frequency of the signal.
Date posted:
September 11, 2019
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Answers (1)
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The chart below shows an arrangement of different parts of the electromagnetic spectrum.Name the radiation represented by B.
(Solved)
The chart below shows an arrangement of different parts of the electromagnetic spectrum.Name the radiation represented by B.
Date posted:
September 11, 2019
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Answers (1)
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A positively charged rod is brought close to the cap of a gold leaf electroscope, it is observed that the gold leaf diverged further. Explain...
(Solved)
A positively charged rod is brought close to the cap of a gold leaf electroscope, it is observed that the gold leaf diverged further. Explain this observation.
Date posted:
September 11, 2019
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Answers (1)
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The figure below shows a circuit contains a battery of cells V, a 3A fuse, F, a switch S, and two identical lamps L1 and...
(Solved)
The figure below shows a circuit contains a battery of cells V, a 3A fuse, F, a switch S, and two identical lamps L1 and L2. A current of 2A flows through lamp L2 when the switch is open.Explain why the fuse may blow when the switch is closed.
Date posted:
September 11, 2019
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Answers (1)
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The figure below shows a set-up used to investigate Charles Law.
(Solved)
The figure below shows a set-up used to investigate Charles Law.
(i) State one missing item in the set-up.
(ii) Name two measurements to be taken in this experiment.
(iii) Explain how the measurements stated above may be used to investigate Charles Law.
Date posted:
September 11, 2019
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Answers (1)
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A small pump develops an average power of 100w it raises water from a borehole to a point 10M above the water level.Calculate the mass...
(Solved)
A small pump develops an average power of 100w it raises water from a borehole to a point 10M above the water level.Calculate the mass of water delivered in 30 minutes.
Date posted:
September 11, 2019
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Answers (1)
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Using the pulley system shown below a mass of 10kg is raised 2M by effort of 80N.
(Solved)
Using the pulley system shown below a mass of 10kg is raised 2M by effort of 80N.
(i) Calculate the distance the effort moves.
(ii) How much potential energy does the load gain.
(iii) How much work is done by the effort?
(iv) What is the efficiency of these pulleys?
Date posted:
September 11, 2019
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Answers (1)
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The figure below shows an object of mass 1kg whirled in a vertical circle of radius 0.5m at a uniform speed of 5m/s.
(Solved)
The figure below shows an object of mass 1kg whirled in a vertical circle of radius 0.5m at a uniform speed of 5m/s.
(i) Determine:
I the centripetal force on the object.
II the tension in the string when the object is at A.
III the tension in the string when the object is at B.
(ii) The speed of rotation is gradually increased until the string snaps. At what point is the string likely to snap. Explain.
Date posted:
September 11, 2019
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Answers (1)
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A rock of mass 150kg moving at 10m/s collides with a stationary rock of mass 100kg. They fuse after collision.Determine the
(i) Total momentum before collision....
(Solved)
A rock of mass 150kg moving at 10m/s collides with a stationary rock of mass 100kg. They fuse after collision.Determine the
(i) Total momentum before collision.
(ii) Total momentum after collision.
(iii) Their common velocity after collision.
Date posted:
September 11, 2019
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Answers (1)
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The figure below shows a balloon filled with air.When the mouth is suddenly opened, the balloon moves in the direction shown by the arrow. Explain...
(Solved)
The figure below shows a balloon filled with air.When the mouth is suddenly opened, the balloon moves in the direction shown by the arrow. Explain that observation.
Date posted:
September 11, 2019
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Answers (1)
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Give a reason why the inside of a helmet is lined with sponge.
(Solved)
Give a reason why the inside of a helmet is lined with sponge.
Date posted:
September 11, 2019
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Answers (1)
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State one application of cooling caused by evaporation.
(Solved)
State one application of cooling caused by evaporation.
Date posted:
September 11, 2019
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Answers (1)
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A certain powder of mass 100g was heated in a container by an electric heater rated 100w for some time. The graph below shows the...
(Solved)
A certain powder of mass 100g was heated in a container by an electric heater rated 100w for some time. The graph below shows the variation of the temperature of the powder with time.
Use the graph to:
(i) Determine the melting point of the powder
(ii) Determine the quantity of heat supplied by the heater from the time the powder starts to melt to the time it has melted.
(iii) Determine the specific latent heat of fusion of the powder assuming the container absorbs negligible amount of heat.
Date posted:
September 11, 2019
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Answers (1)