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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
Why does the cord of an electric heater not glow while the heating element does?
Why is the tungsten used almost exclusively for filament of electric lamps?
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
When current is switched ‘on’ in a room heater, it ______.
Why is a series arrangement not used for connecting domestic electrical appliances in a circuit?
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.
A heating coil has a resistance of 200 Ω. At what rate will heat be produced in it when a current of 2.5 A flows through it?
The heat produced in a wire of resistance 'x' when a current 'y' flows through it in time 'z' is given by:
(a) x2 × y × z
(b) x × z × y2
(c) y × z2 × x
(d) y × z × x
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.
An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at ‘minimum heating' it consumes a power of 360 W but at 'maximum heating’ it takes a power of 840 W. Calculate the current and resistance in each case.
Give a scientific reason.
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1 A = ____________ mA.
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Right or wrong sentence.
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Name some devices that run using heat effect of electric current
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Why is parallel arrangement used in domestic wiring?
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- circuit is open.
- no current flows through it.
- current flows after some time.
Choose the combination of correct answer from the following.
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What are the uses of electromagnets?
Match the following
| 1. | Bulb | a. | Conductor |
| 2. | Electroplating | b. |
Insulator |
| 3. | Pure water | c. | Heating effect of current |
| 4. | Salt solution | d. | Chemical effect of current |
Name the effect of the current responsible for the glow of the bulb in an electrical circuit.
An electrochemical cell converts ______ energy into ______ energy.
A trip switch is a ______ safety device.
Explain why fuse wire is always connected in a series arrangement.
Find the odd one out.
1 kWh is equal to ______.
What is the heating effect of electric current?
Anannya responded to the question: Why do electrical appliances with metallic bodies are connected to the mains through a three-pin plug, whereas an electric bulb can be connected with a two-pin plug?
She wrote: Three-pin connections reduce heating of connecting wires.
- Is her answer correct or incorrect? Justify.
- What is the function of a fuse in a domestic circuit?
