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प्रश्न
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
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उत्तर
The coils of the heating elements of electric irons and electric toasters are made of alloys like nichrome rather than a pure metal because alloys have a high resistance and a high melting point.
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संबंधित 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?
Write Joule's law of heating.
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
What is meant by the heating effect of current? Give two applications of the heating effect of current.
The elements of electrical heating devices are usually made of:
(a) tungsten
(b) bronze
(c) nichrome
(d) argon
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.
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.
Give a scientific reason.
Tungsten metal is used to make a solenoid type coil in an electric bulb.
Solve the following question.
Compute the heat generated while transferring 96000 coulombs of charge in two hours through a potential difference of 40 V.
What is a short circuit?
Explain the application of heating effect of electric current in an electric bulb with a diagram.
Which of the following gases are filled in electric bulbs?
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.
What are the factors affecting heating effect of electric current?
Copper wire offers very little ______ and does not get heated up quickly.
Name a few appliances which work on the basis of the heating effect of current.
An electrochemical cell converts ______ energy into ______ energy.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
In which of the following applications of Iron, rusting will occur most? Support your answer with valid reason.
| A | B | C | D |
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