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प्रश्न
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
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उत्तर
The conductors of electric heating devices, such as bread toasters and electric irons, are made of alloy instead of pure metal for the following reasons:
- The resistivity of an alloy is higher than that of a metal, which produces a large amount of heat.
- Oxidation of alloys does not occur quickly at high temperatures.
- There is a negligible change in their resistance with an increase in temperature.
संबंधित प्रश्न
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
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(a) chemical effect of current
(b) magnetic effect of current
(c) lighting effect of current
(d) heating effect of current
The electrical resistivities of four materials P, Q, R and S are given below:
| P | `6.84xx10^8`Ωm |
| Q | `1.70xx10^8`Ωm |
| R | ` 1.0xx10^15`Ωm |
| s | `11.0xx10^-7`Ωm |
Which material will you use for making: (a) heating element of electric iron (b) connecting wires of electric iron (c) covering of connecting wires? Give reason for your choice in each case.
Identify the figure and give its use.
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.
A coil of an alloy _______ is used in electric heater cooker as a resistor.
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.
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When a switch is in OFF position,
- circuit starting from the positive terminal of the cell stops at the switch.
- circuit is open.
- no current flows through it.
- current flows after some time.
Choose the combination of correct answer from the following.
An electric cell produces electricity from the ______ ______ in it.
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 |
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.
An electrochemical cell converts ______ energy into ______ energy.
A trip switch is a ______ safety device.
1 kWh is equal to ______.
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
