Which of the following device reverses the direction of flow of current through a circuit ?
Commutator
Rheostat
Ammeter
Voltmeter
The charged body at rest produces
Electric field
Magnetic field
Neither A or B
Both A & B
SI unit of magnetic field is
Tesla
Volt
Joule
Ampere
The wire having black plastic covering is a
Live wire
Neutral wire
Earth wire
None
The wire having a green plastic covering is a
The regions of concentrated magnetic strength inside the magnet just near its ends are
Magnetic poles
Magnetic Ends
None of these
Electromagnets are used in
Electric bells
Telephone
Dynamo
All of these
The safety device to protect an electric circuit from overloading or short circuiting is
Earthing
Electric fuse
Magnetic induction
Electrolysis
Choose correct statement about magnetic lines of force
Lines of force are not imaginary lines
Can not be mapped on paper
Do not intersect each other
Always intersect each other.
An electric generator actually act as a
Source of electric charge
Source of heat energy
Electromagnet
Converter of energy
