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For a certain radioactive material, the average count-rate is found to be 82 counts per second. After 210 seconds, the count rate had dropped by...
(Solved)
For a certain radioactive material, the average count-rate is found to be 82 counts per second. After 210 seconds, the count rate had dropped by 63 counts per second. The average background count-rate remained constant at 10 counts per second. What is the half-life of the material?
Date posted:
June 3, 2019
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Answers (1)
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The figure below shows the wiring in a modern main appliance.
(i) Identify the colour of wires Y and Z.
(ii) A cooker rated 2.0KW was...
(Solved)
The figure below shows the wiring in a modern main appliance.
(i) Identify the colour of wires Y and Z.
(ii) A cooker rated 2.0KW was operated for 35 minutes each day for 30 days.
If the cost of each unit is Sh.12.5 Calculate the cost of electricity used.
Date posted:
June 3, 2019
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Answers (1)
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State the adjustments that can be made on a d.c generator to produce alternating current.
(Solved)
State the adjustments that can be made on a d.c generator to produce alternating current.
Date posted:
June 3, 2019
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Answers (1)
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A transformer is used on a 240V a.c supply to deliver 12A at 120V to a heating coil. If 20% energy is lost at the...
(Solved)
A transformer is used on a 240V a.c supply to deliver 12A at 120V to a heating coil. If 20% energy is lost at the transformer, calculate the current in the primary coil.
Date posted:
June 3, 2019
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Answers (1)
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The diagram below shows an induction coil used to produce sparks.
(i) Name the part labelled C.
(ii) Explain why the part labelled A is thicker than...
(Solved)
The diagram below shows an induction coil used to produce sparks.
(i) Name the part labelled C.
(ii) Explain why the part labelled A is thicker than C.
(iii) State the purpose of part labelled B.
Date posted:
June 3, 2019
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Answers (1)
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In a compound microscope, the focal length of the objective lens is 3.0cm and that of the eye piece is 3.2cm and they are placed...
(Solved)
In a compound microscope, the focal length of the objective lens is 3.0cm and that of the eye piece is 3.2cm and they are placed 10.0cm apart. An object is placed 5cm from the objective lens. Use the lens formular. In turn for each lens to find the position of the final image.
Date posted:
June 3, 2019
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Answers (1)
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Figure below shows sound waves emitted by a drum struck.
Explain why the wave fronts are directed towards the ground.
(Solved)
Figure below shows sound waves emitted by a drum struck.
Explain why the wave fronts are directed towards the ground.
Date posted:
June 3, 2019
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Answers (1)
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A student set up a mass attached to a spring such that when it oscillates, it taps on water surface in a wide shallow tank.
The...
(Solved)
A student set up a mass attached to a spring such that when it oscillates, it taps on water surface in a wide shallow tank.
The student measured time for 20 oscillations and found that the mass takes 36 seconds. Given that the student counted four rippies between the mass and end B of the tank. Determine the speed of the waves.
Date posted:
June 3, 2019
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Answers (1)
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State two properties of an image formed by a concave mirror that makes it suitable for use by barbers.
(Solved)
State two properties of an image formed by a concave mirror that makes it suitable for use by barbers.
Date posted:
June 3, 2019
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Answers (1)
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Define focal plane.
(Solved)
Define focal plane.
Date posted:
June 3, 2019
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Answers (1)
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Figure below shows a current carrying conductor placed perpendicularly between the poles of a magnet.
(i) Show on the diagram the magnetic field pattern.
(ii) The...
(Solved)
Figure below shows a current carrying conductor placed perpendicularly between the poles of a magnet.
(i) Show on the diagram the magnetic field pattern.
(ii) The direction of net force on the conductor.
Date posted:
June 3, 2019
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Answers (1)
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The table below shows the type of radiation detection method and uses of electro-magnetic radiations. Complete the table.
(Solved)
The table below shows the type of radiation detection method and uses of electro-magnetic radiations. Complete the table.
Date posted:
June 3, 2019
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Answers (1)
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The figure below shows an electroscope being charged by induction.
(i) State the reason why the cap of the electroscope is made circular.
(ii) On the...
(Solved)
The figure below shows an electroscope being charged by induction.
(i) State the reason why the cap of the electroscope is made circular.
(ii) On the same diagram, show the direction of the flow of electrons on the earth wire.
Date posted:
June 3, 2019
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Answers (1)
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Figure below shows an image formed in a plane mirror.
By drawing incident rays for the rays shown, locate the position of the object.
(Solved)
Figure below shows an image formed in a plane mirror.
By drawing incident rays for the rays shown, locate the position of the object.
Date posted:
June 3, 2019
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Answers (1)
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The figure below shows rectangular block of height 4cm floating vertically in a beaker containing two
immiscible liquid A and B. The densities of the liquid...
(Solved)
The figure below shows rectangular block of height 4cm floating vertically in a beaker containing two
immiscible liquid A and B. The densities of the liquid are 8000 kg/m³ and 12,000kg/m³ respectively.
The cross sectional area is 2cm².
Determine.
(i) the weight of the liquid A displaced by the black.
(ii) the weight of the liquid B displaced by the block.
(iii) the mass of the block.
(iv) the density of the block.
Date posted:
June 3, 2019
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Answers (1)
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A man uses the inclined plane to lift a 50kg load through a vertical line height of 4.0m. The inclined plane makes an angle of...
(Solved)
A man uses the inclined plane to lift a 50kg load through a vertical line height of 4.0m. The inclined plane makes an angle of 300 with the horizontal. If the efficiency of the inclined plane is 80%, determine.
(a) The effort needed to move the load up the inclined plane at a constant velocity.
(b) The work done against friction in raising the load through the height of 4.0m. (Take g = 10N/kg).
Date posted:
June 3, 2019
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Answers (1)
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A minibus of mass 1600kg travelling at a constant velocity of 20mls collides with a stationary car of mass 800kg. The impact takes 2 seconds...
(Solved)
A minibus of mass 1600kg travelling at a constant velocity of 20mls collides with a stationary car of mass 800kg. The impact takes 2 seconds before the two moves together and come to rest after 15 seconds. Determine.
(a) The common velocity.
(b) The distance moved after the impact.
(c) The impulse force.
Date posted:
June 3, 2019
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Answers (1)
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What is meant by perfectly inelastic collision.
(Solved)
What is meant by perfectly inelastic collision.
Date posted:
June 3, 2019
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Answers (1)
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The moon goes round the earth at a constant speed. Explain why it is true to say the moon is accelerating.
(Solved)
The moon goes round the earth at a constant speed. Explain why it is true to say the moon is accelerating.
Date posted:
June 3, 2019
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Answers (1)
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A block of metal of mass 150g at 1000C is dropped into a lagged calorimeter of heat capacity 40Jk-1 containing 100g of water at 250C....
(Solved)
A block of metal of mass 150g at 1000C is dropped into a lagged calorimeter of heat capacity 40Jk-1 containing 100g of water at 250C. The temperature of the resulting mixture is 340C. (Specific heat capacity of water = 4200Jkgˉ¹).
Determine;
(i) Heat gained by calorimeter.
(ii) Heat gained by water.
(iii) Heat lost by the metal block.
(iv) Specific heat capacity of the metal block.
Date posted:
June 3, 2019
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Answers (1)