Advertisements
Advertisements
Question
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
Advertisements
Solution
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 metal, which produces a large amount of heat.
- Oxidation of alloys does not occur quickly at high temperatures.
- There is negligible change in their resistance with increase in temperature.
APPEARS IN
RELATED QUESTIONS
Why does the cord of an electric heater not glow while the heating element does?
When current is switched ‘on’ in a room heater, it ______.
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
How does the resistance of a wire vary with its:
diameter?
Explain why, tungsten is used for making the filaments of electric bulbs.
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
The current passing through an electric kettle has been doubled. The heat produced will become:
(a) half
(b) double
(c) four time
(d) one-fourth
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.
An electric iron of 1100 W is operated for 2 hrs daily. What will be the electrical consumption expenses for that in the month of April? (The electric company charges Rs 5 per unit of energy).
Why does tungsten metal used to make solenoid type coil in an electric bulb?
In an electric bulb, coil of _______ metal is used.
These days when current in the circuit suddenly increases _______ switches are used.
Which metal is used to make the filament of an electric bulb?
Which of the following is correct?
What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
What are the uses of electromagnets?
Explain the working of an electric fuse.
Fuse is a strip of alloy wire which is made up of lead and tin with a very low ______.
A student boils water in an electric kettle for 20 minutes. Using the same mains supply he wants to reduce the boiling time of water. To do so should he increase or decrease the length of the heating element? Justify your answer.
