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The number of electrons reaching the screen (that determine the brightness of the beam) is controlled by making the grid less negative or more negative.
johnmulu answered the question on February 20, 2017 at 05:54
- State two factors that determine the resistance of metallic conductor and explain how a fuse safeguards electrical appliances against excessive currents.(Solved)
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. Answers (1)
- When a transformer is connected to ac source, the output voltage is found to be 24 V. If the power input is 200 W,(Solved)
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. Answers (1)
- In domestic wiring systems lamps in the circuit are required to be in parallel and not in series. State two reasons for this requirement. (Solved)
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. Answers (1)
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A house has one 100 W bulb, two 60 W bulbs and one 30 W bulb. Determine the cost of having all the bulbs switched on for 70 hours, given that the cost of electricity is 40 cents per kilowatt hour.
(Solved)
A house has one 100W bulb, two 60 W bulbs and one 30 W bulb. Determine the cost of having all the bulbs switched on for 70 hours, given that the cost of electricity is 40 cents per kilowatt hour.
Date posted: February 20, 2017. Answers (1)
- State the reason why electrical power is transmitted over long distances at very high voltage(Solved)
State the reason why electrical power is transmitted over long distances at very high voltage
Date posted: February 20, 2017. Answers (1)
- How many 1000w electric irons could be safely connected to a 240 V main circuit fitted with 13 A fuse?(Solved)
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. Answers (1)
- 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;(Solved)
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. Answers (1)
- What is meant by the term “electromagnetic induction”?(Solved)
State what is meant by the term “electromagnetic induction”.
Date posted: February 20, 2017. Answers (1)
- Why is electric power is transmitted over long distances at high voltage?(Solved)
Explain why electric power is transmitted over long distances at high voltage.
Date posted: February 20, 2017. Answers (1)
- Explain how energy losses in a transformer are reduced by having:
(Solved)
Explain how energy losses in a transformer are reduced by having:
(i) A soft-iron core-
(ii) A laminated core
Date posted: February 20, 2017. Answers (1)
- State Lenz’s Law of electromagnetic induction.(Solved)
State Lenz’s Law of electromagnetic induction.
Date posted: February 20, 2017. Answers (1)
- What causes electromagnetic damping in a moving coil galvanometer?(Solved)
What causes electromagnetic damping in a moving coil galvanometer?
Date posted: February 18, 2017. Answers (1)
- State the laws of electromagnetic induction.(Solved)
State the laws of electromagnetic induction.
Date posted: February 18, 2017. Answers (1)
- Radiant heat from the sun penetrates a glass sheet while radiant heat from burning wood is cut off by the glass sheet. Explain(Solved)
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. Answers (1)
- State the difference between X-rays and gamma rays in the way in which they are produced.(Solved)
State the difference between X-rays and gamma rays in the way in which they are produced.
Date posted: February 18, 2017. Answers (1)
- State the reasons why radio waves signals are easier to receive than TV (television) signals in a place surrounded by hills (Solved)
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. Answers (1)
- State two uses of microwaves.(Solved)
State two uses of microwaves.
Date posted: February 18, 2017. Answers (1)
- Arrange the following in order of increasing frequencies (Solved)
Arrange the following in order of increasing frequencies - Gamma radiation, Radio waves, Infrared, and X - rays
Date posted: February 18, 2017. Answers (1)
- A balloon is filled with a gas which is lighter than air. It is observed to rise in air up to a certain height.(Solved)
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. Answers (1)
- a)State the condition necessary for a body to float in fluid
b) A ship made of steel is observed to float on water yet the density of steel is approximately eight times that of water(Solved)
a) State the condition necessary for a body to float in fluid
b) A ship made of steel is observed to float on water yet the density of steel is approximately eight times that of water. Explain this observation.
Date posted: February 18, 2017. Answers (1)