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प्रश्न
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
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उत्तर
Nichrome is used to make the heating elements of electrical appliances because it has a high resistance and a high melting point.
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संबंधित प्रश्न
Write Joule's law of heating.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
Why does the connecting cord of an electric heater not glow hot while the heating element does?
Two exactly similar heating resistances are connected (i) in series, and (ii) in parallel, in two different circuits, one by one. If the same current is passed through both the combinations, is more heat obtained per minute when they are connected in series or when they are connected in parallel? Give reason for your answer.
Which electric heating device in your home do you think have resistors which control the flow of electricity?
Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply. Calculate:
- the total current taken from the supply
- the resistance of each heater and
- the energy supplied in kWh to the three heaters in 5 hours.
Write the mathematical expression for Joule’s law of heating.
What is the heating effect of electric current?
Define fuse.
An electric bulb is connected to a 220 V generator. The current is 0.50 A. What is the power of the bulb?
Unscramble the following words:
SFEU
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
Your teacher has shown you the following activity.
Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in the following figure. The current is switched on and some pins are placed near the ends of the nail.
Write down any three questions that come to your mind about this activity.
Explain the working of an electric fuse.
Assertion: A current-carrying wire should be charged.
Reason: The current in a wire is due to the flow of free electrons in a definite direction.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
Find the odd one out.
An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?
The graph of voltage vs current for four different materials is shown below.
Which of these four materials would be used for making filament of bulb?
