Advertisements
Advertisements
Question
Explain the construction and working of an Telephone.
Advertisements
Solution
In telephones, a changing magnetic effect causes a thin sheet of metal (diaphragm) to vibrate. The diaphragm is made up a metal that can be attracted to magnets.
- The diaphragm is attached to spring that is fixed to the earpiece.
- When a current flows through the wires, the soft – iron bar becomes an electromagnet.
- The diaphragm becomes attracted to the electromagnet.
- As the person on the other end of the line speaks, his voice cause the current in the circuit to change. This causes the diaphragm in the earpiece to vibrate, producing sound.
APPEARS IN
RELATED QUESTIONS
One unit of coulomb is charge of approximately ______ protons or electrons.
Match the following
| 1. | Cell | used to open or close a circuit |
| 2. | Switch | safety device used in electric circuit |
| 3. | Circuit | A complete path for the flow of an electric current |
| 4. | Miniature circuit Breaker | Reset by hand, circuit becomes complete once again |
| 5. | Fuse | A device which converts chemical energy into electrical energy |
Give a reason for the following.
One should not use an umbrella while crossing an open field during thunderstorm.
A cell, a resistor, a key and ammeter are arranged as shown in the circuit diagrams of Figure. The current recorded in the ammeter will be
 |
 |
 |
| (i) | (ii) | (iii) |
Electrical resistivity of a given metallic wire depends upon
Which of the following precautions need not be taken while using electric gadgets/appliances/circuit?
Why are compact fluorescent lamps (CFLs) preferred over electric bulbs?
Why is an electric fuse required in all electrical appliances?
Electricity produced on rubbing is ______.
A torch is not functioning, though contact points in the torch are in working condition. What can be the possible reasons for this? Mention any three.
