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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
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
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Write Joule's law of heating.
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Why does the connecting cord of an electric heater not glow hot while the heating element does?
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
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A resistance of 25 Ω is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
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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
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Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Identify the figure and give its use.
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Why does tungsten metal used to make solenoid type coil in an electric bulb?
Give scientific reason :
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster, etc., an alloy such as Nichrome is used, not pure metals.
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.
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Write the mathematical expression for Joule’s law of heating.
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Name any two appliances which works on the phenomenon of heating effect of electric current.
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- Will the bulb in the two circuits glow with the same brightness? Justify your answer.
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(a) Observe the diagram given below and state whether the bulb will glow or not when we switch on K.
(b) Is it safe to handle the bulb when the switch is OFF?
(c) Give a reason for your answer in (b).
An electric component used as a safety device is electric circuit is ______.
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______ wire is used in the filament of the bulbs.
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A trip switch is a ______ safety device.
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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?
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- kilowatt hour and
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An electric iron of resistance 20 Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is ______.
