Advertisements
Advertisements
Question
Explain the construction and working of an Telephone.
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
Two identical resistros of `12 Omega` each are connected to a battery of 3V . Calculate the ratio of the power consumed by the resulting combinations with minimum resistance and maximum resistance.
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 |
Length: metre scale: : Current: ______
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) |
Which of the following solutions will not make the bulb glow in figure?
Name the effect of current responsible for the glow of the bulb in an electric circuit.
Which of the following precautions need not be taken while using electric gadgets/appliances/circuits?
Draw the symbols of the following circuit components.
electric bulb
