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प्रश्न
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
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उत्तर
The performance and life of a heating element are determined by the material used to make the heating element. The heating element material must have a high melting point, high tensile strength, high resistivity, and a low-temperature coefficient of resistance. Because an alloy's resistivity is greater than that of pure metal, alloys are employed in electrical heating devices rather than pure metals. Furthermore, even at greater temperatures, the alloy does not easily burn (or oxidise).
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संबंधित प्रश्न
Name any two effects of electric current.
Write Joule's law of heating.
What is nichrome? State its one use.
How does the resistance of a wire vary with its:
diameter?
An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.
How much heat will an instrument of 12 W produce in one minute if it is connected to the heat produced by it?
The current passing through a room heater has been halved. What will happen to the heat produced by it?
The heat produced by passing an electric current through a fixed resistor is proportional to the square of:
(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed
If the current flowing through a fixed resistor is halved, the heat produced in it will become:
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.
Give a scientific reason.
Tungsten metal is used to make a solenoid type coil in an electric bulb.
Identify the figure and give its use.
Heat energy is being produced in a resistance in a circuit at the rate of 100 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance?
Name the factors on which the heat produced in a wire depends when current is passed in it, and state how does it depend on the factors stated by you.
Rewrite the following statement by selecting the correct option:
1 A = ____________ mA.
Write the mathematical expression for Joule’s law of heating.
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
When does overloading occur?
What does overloading cause?
Explain the application of heating effect of electric current in an electric bulb with a diagram.
Mark the correct choice
- Assertion: Electric appliances with a metallic body have three wire connections.
- Reason: Three-pin connections reduce the heating of the connecting wires.
The heating element of an electric iron is made up of:
Which of the following gases are filled in electric bulbs?
Why is parallel arrangement used in domestic wiring?
Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit another set of three bulbs of the same wattage are connected in parallel to the same source.
- Will the bulb in the two circuits glow with the same brightness? Justify your answer.
- Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
An electric component used as a safety device is electric circuit is ______.
Unscramble the following words:
SFEU
What are the uses of electromagnets?
______ wire is used in the filament of the bulbs.
Name a few appliances which work on the basis of the heating effect of current.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
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?
An electric kettle of 2 kW is used for 2h. Calculate the energy consumed in
- kilowatt hour and
- joules.
Write an expression for the amount of heat produced in a resistor when an electric current is passed through it stating the meanings of the symbols used.
