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Name the metal used to shields X-rays operators from the radiation. Give a reason why it is used.
Date posted:
February 20, 2017
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Name two differences between cathode rays and electromagnetic radiations.
Date posted:
February 20, 2017
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State two differences between the cathode ray tube (CRT) of a T.V. and the cathode ray oscilloscope (CRO).
Date posted:
February 20, 2017
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The control grids in a Cathode Ray Oscilloscope (CRO) is used to control the brightness of the beam on the screen. How is this achieved?
Date posted:
February 20, 2017
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a) State two factors that determine the resistance of metallic conductor.
b) Explain how a fuse safeguards electrical appliances against excessive currents.
c) A hair dryer is rated 2.5kW, 240 V.
i) Determine whether a 10 A fuse may be suitable for the hair dryer
ii) Determine the cost of using the dryer for 3 hours if the cost of electricity is Ksh. 0.80 per kilowatt hour.
Date posted:
February 20, 2017
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When a transformer is connected to ac source, the output voltage is found to be 24 V. If the power input is 200 W, determine the output current. (Assume the transformer is 100% efficient)
Date posted:
February 20, 2017
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In domestic wiring systems lamps in the circuit are required to be in parallel and not in series. State two reasons for this requirement.
Date posted:
February 20, 2017
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State the reason why electrical power is transmitted over long distances at very high voltage
Date posted:
February 20, 2017
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How many 1000w electric irons could be safely connected to a 240 V main circuit fitted with 13 A fuse?
Date posted:
February 20, 2017
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In a transformer, the ratio of primary turns to the secondary turns is 1:10. A. A current 500mA flows through a 200$\Omega$ resistor in the secondary circuit. Assuming that the transformer is 100% efficient, determine;
(i) The secondary voltage
(ii) The primary voltage;
Date posted:
February 20, 2017
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State what is meant by the term “electromagnetic induction”.
Date posted:
February 20, 2017
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Explain why electric power is transmitted over long distances at high voltage.
Date posted:
February 20, 2017
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State Lenz’s Law of electromagnetic induction.
Date posted:
February 20, 2017
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What causes electromagnetic damping in a moving coil galvanometer?
Date posted:
February 18, 2017
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State the laws of electromagnetic induction.
Date posted:
February 18, 2017
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Explain the fact that radiant heat from the sun penetrates a glass sheet while radiant heat from burning wood is cut off by the glass sheet.
Date posted:
February 18, 2017
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State the difference between X-rays and gamma rays in the way in which they are produced.
Date posted:
February 18, 2017
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State the reasons why radio waves signals are easier to receive than TV (television) signals in a place surrounded by hills
Date posted:
February 18, 2017
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State two uses of microwaves.
Date posted:
February 18, 2017
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Arrange the following in order of increasing frequencies - Gamma radiation, Radio waves, Infrared, and X - rays
Date posted:
February 18, 2017
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A balloon is filled with a gas which is lighter than air. It is observed to rise in air up to a certain height. State a reason why the balloon stops rising.
Date posted:
February 18, 2017
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State the law of flotation
Date posted:
February 18, 2017
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When a piece of metal is placed on water, it sinks. But when the same piece of metal is placed on a block of wood, both are found to float. Explain this observation.
Date posted:
February 18, 2017
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A block of glass of mass 250 g floats in mercury. What volume of glass lies under the surface of the mercury? (Density of mercury is 13.6 x 103Kgm-3)
Date posted:
February 18, 2017
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A block of wood weighing 2.0 N is held under water by a string attached to the bottom of a container. The tension in the string is 0.5 N. Determine the density of the wood.
Date posted:
February 18, 2017
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Explain the following observation: Ice cubes float on water and solid benzene sinks in liquid benzene
Date posted:
February 18, 2017
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A solid copper sphere will sink in water while a hollow copper sphere of the same mass may float. Explain this observation.
Date posted:
February 18, 2017
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a) When a bus goes a round bend on a flat road, it experiences a centripetal force. State what provides the centripetal force
b) State the purpose of banking roads at bends.
Date posted:
February 18, 2017
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Explain applications of uniform circular motion in daily life.
Date posted:
February 18, 2017
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State two ways in which the centripetal force on a body can be increased.
Date posted:
February 18, 2017