Ch# 18 Magnetic Fields

Solenoid

It's a long, tightly wound, cylindrical coil of wire. When a current passes through the winding of a solenoid, a magnetic field is produced and the solenoid then starts behaving like a bar-magnet.

Toroid

It's a circular solenoid. It's a coil of insulated copper wire wounded on a circular core with close turns.

Ampere's law

Consider a long straight wire carrying “I" current and a closed curve containing circle of radius” r” with wire at the centre.

Value of the ratio e/m is?

1.7588×10^11 coulomb/kg

Galvanometer

It's an instrument used to detect and measure electric currents. It's a highly sensitive electromagnetic apparatus capable of measuring even small amounts of current, such as those on the order of a few micro amperes.