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The primary coil of a transformer has 1200 turns and the secondary coil has 60 turns. The transformer is connected to a 240 V a.c source. (i) The output...
(Solved)
The primary coil of a transformer has 1200 turns and the secondary coil has 60 turns. The transformer is connected to a 240V a.c source.
i) The output voltage.
ii) The output current when the primary coil has a current of 0.5A (Assume there is no energy losses)
iii) One of the primary ways in which power is lost in transformers is through eddy currents. State how eddy currents can be
minimized.
Date posted:
May 30, 2019
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Answers (1)
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In an experiment to determine the speed of sound, an observer stood in front of a high wall at a distance of 80m. He
clapped two...
(Solved)
In an experiment to determine the speed of sound, an observer stood in front of a high wall at a distance of 80m. He
clapped two boards together at such a rate that each clap coincided with the echo from the wall. A second observer noted
a time of 9.5 seconds starting with first clap and ending with the 21st clap.
i) Calculate the speed of sound under these conditions.
ii) Describe one probable source of error in this experiment.
iii) State one way in which sound wave differ from light waves.
Date posted:
May 30, 2019
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Answers (1)
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The speed of sound in air determined on a warm day is 330m/s. Explain any difference you would expect in the results if
the measurement is...
(Solved)
The speed of sound in air determined on a warm day is 330m/s. Explain any difference you would expect in the results if
the measurement is done on a cold day.
Date posted:
May 30, 2019
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Answers (1)
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The figure below is a sketch of ripples caused by a vibrator in a ripple tank whose frequency is 50Hz.
Using the above information, determine the...
(Solved)
The figure below is a sketch of ripples caused by a vibrator in a ripple tank whose frequency is 50Hz
Using the above information, determine the speed of the wave motion.
Date posted:
May 30, 2019
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Answers (1)
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A person standing behind a wall hears a bell ringing although he cannot see the bell. What property of sound enables him
to hear the sound?
(Solved)
A person standing behind a wall hears a bell ringing although he cannot see the bell. What property of sound enables him
to hear the sound?
Date posted:
May 30, 2019
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Answers (1)
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A wire was connected to a battery and it was found that the energy converted to heat was 30J when 20 coulombs of
charge flowed through...
(Solved)
A wire was connected to a battery and it was found that the energy converted to heat was 30J when 20 coulombs of
charge flowed through the wire in 5 seconds
Calculate
i) The p.d. between the ends of the wire.
ii) The current flowing through the wire.
iii) The resistance of the wire.
iv) The power developed in the wire.
Date posted:
May 30, 2019
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Answers (1)
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Form four students performed an experiment in photoelectric effect and drew the graph below from the data collected.
From the graph determine
i) threshold frequency.
ii) Planks...
(Solved)
Form four students performed an experiment in photoelectric effect and drew the graph below from the data collected.
From the graph determine
i) threshold frequency.
ii) Planks constant . (Take charge on an electron, e = 1.6×10-19C)
Date posted:
May 30, 2019
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Answers (1)
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The figure below shows the construction and circuit of the modern physics X-ray tube.
a) Indicate on the diagram the path of the x-ray beam.
b)...
(Solved)
The figure below shows the construction and circuit of the modern physics X-ray tube.
a) Indicate on the diagram the path of the x-ray beam.
b) Name the part marked C and state its function
c) Name the metal used in parts A and B and state why they are suitable for use in the tube.
d) Why are cooling fins necessary?
Date posted:
May 30, 2019
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Answers (1)
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Explain why it is not advisable to use a 10A fuse for a hair dryer rated 2.5Kw, 240V.
(Solved)
Explain why it is not advisable to use a 10A fuse for a hair drier rated 2.5Kw, 240V.
Date posted:
May 30, 2019
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Answers (1)
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State how polarization is reduced in a simple cell.
(Solved)
State how polarization is reduced in a simple cell.
Date posted:
May 30, 2019
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Answers (1)
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Find the combined capacitance between points A and B of the arrangement shown in the figure below.
(Solved)
Find the combined capacitance between points A and B of the arrangement shown in the figure below.
Date posted:
May 30, 2019
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Answers (1)
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Explain why the cathode of a CRO is coated with oxides of metals such as Barium and Strontium.
(Solved)
Explain why the cathode of a CRO is coated with oxides of metals such as Barium and Strontium.
Date posted:
May 30, 2019
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Answers (1)
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The figure below shows a coil and a magnet being removed from the coil.
a) State the polarity gained at end B.
b) Indicate the direction...
(Solved)
The figure below shows a coil and a magnet being removed from the coil.
a) State the polarity gained at end B.
b) Indicate the direction of flow of current on the coil.
Date posted:
May 30, 2019
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Answers (1)
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A ray from a source X makes an angle of 30° with a plane reflector and a ray from a source Y makes an angle...
(Solved)
A ray from a source X makes an angle of 30° with a plane reflector and a ray from a source Y makes an angle of 60° to the
same reflector at the same point M as shown below. Find the angle through which the reflector at the same point M as shown
below. Find the angle through which the reflector must be rotated about M such that the ray from the source Y falls on the
source X.
Date posted:
May 30, 2019
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Answers (1)
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A box of mass 500g has dimension 10m × 5m × 3m. Determine the maximum pressure exerted by the box on a flat surface. (Take...
(Solved)
A box of mass 500g has dimension 10m × 5m × 3m. Determine the maximum pressure exerted by the box on a flat surface. (Take g = 10N/kg)
Date posted:
May 30, 2019
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Answers (1)
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The figure below represents a hydraulic brake.
A force of 20N is applied on the foot pedal connected to a piston of area 0.0005m² and this...
(Solved)
The figure below represents a hydraulic brake.
A force of 20N is applied on the foot pedal connected to a piston of area 0.0005m² and this causes a stopping force of 5000N. Calculate
i) The pressure in the master cylinder.
ii) The area of the slave piston.
iii) The velocity ratio
Date posted:
May 30, 2019
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Answers (1)
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A driver driving a car of mass 1200kg at a constant speed of 72km/h is flagged down by a traffic police officer 145m
away. It takes...
(Solved)
A driver driving a car of mass 1200kg at a constant speed of 72km/h is flagged down by a traffic police officer 145m
away. It takes him 2 seconds to react to the police signal and brings the car to rest by applying a constant breaking force in 10 seconds. Determine.
i) The minimum stopping distance.
ii) State whether it will hit the traffic police officer or not.
Date posted:
May 30, 2019
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Answers (1)
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A bus of mass 5,000kg and a car of mass 1200kg are both travelling on a dual carriage way at the same velocity. If both
drivers...
(Solved)
A bus of mass 5,000kg and a car of mass 1200kg are both travelling on a dual carriage way at the same velocity. If both
drivers apply the same breaking force. State with reason which one will come to stop first.
Date posted:
May 30, 2019
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Answers (1)
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The weight of cube in air is 0.25N. When immersed in water, it weighs 0.44N and when in oil weighs 0.46N. Calculate the relative density...
(Solved)
The weight of cube in air is 0.25N. When immersed in water, it weighs 0.44N and when in oil weighs 0.46N. Calculate the relative density of the oil.
Date posted:
May 30, 2019
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Answers (1)
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A block of glass of mass 0.25kg floats in mercury of density 1.36 × 104kg/m³. What volume of the glass lies under the surface of...
(Solved)
A block of glass of mass 0.25kg floats in mercury of density 1.36 × 104kg/m³. What volume of the glass lies under the surface of mercury?
Date posted:
May 30, 2019
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Answers (1)