Electricity and magnetism are two sides of the same coin. This chapter turns current into motion (the motor) and motion into current (the generator).
Q1. Why is the fuse always connected in the live wire of a household circuit?
A fuse is a safety device that melts when the current exceeds a safe value.
It is placed in the LIVE wire so that when it blows, it disconnects the appliance from the high-potential supply.
This stops any current from reaching the appliance and prevents fire or shock.
Q2. State how you can increase the strength of the magnetic field of a solenoid (electromagnet).
Increase the current through the coil.
Increase the number of turns per unit length.
Insert a soft-iron core inside the solenoid.
| Quantity | Formula | SI unit |
|---|---|---|
| Force direction on current | Fleming's left-hand rule | — |
| Induced current direction | Fleming's right-hand rule | — |
| Frequency of AC (India) | 50 Hz (changes direction 100×/s) | hertz |
| Domestic voltage (India) | 220 V, live–neutral | volt |
Both convert mechanical energy to electrical, but an AC generator uses slip rings (current reverses each half-turn) while a DC generator uses a split-ring commutator to give current in one direction.
If the thumb, forefinger and middle finger of the left hand are held mutually perpendicular, the forefinger points along the field, the middle finger along the current, and the thumb gives the direction of force on the conductor.
The production of an induced current in a coil due to a change in the magnetic field (flux) linked with it — the principle of the electric generator.
Because the magnetic field of the current interacts with the external magnetic field, producing a force whose direction is given by Fleming's left-hand rule.
Hi! Found an error or have a suggestion? Let us know and we'll fix it.
Thanks! Your feedback has been sent. We'll look into it.