1.
The fact that current is associated with a magnetic field was discovered by
2.
Choose the correct statement:
3.
The unit of induced emf is
4.
By inserting a soft iron piece into a solenoid, the strength of the magnetic field
5.
The coil of a heater is cut into two equal halves and only one of them is used in the beater. The ratio of the heat produced by this half of the col to that produced by the original coil is
7.
Fleming's right hand rule gives
8.
Ampere rule is used to find the
9.
If current in the core decreases, the strength of the magnetic field
10.
The unit of magnetic flux is
11.
A magnetic field cannot exert any force on a
12.
By increasing the number of turns in the coil, the strength of the magnetic field
14.
The resistance of a conductor is reduced to half its initial value. In doing so the heating effects in the conductor will become
15.
The force of repulsion between two parallel wires is f when each one of them carries a certain current /. If the current in each is doubled, the force between them would be
16.
It is a common notion that the earth's magnetism is due to the
17.
A compass needle just above a wire in which electrons are moving towards east, will point
18.
A magnetic field can exert force on a
19.
The force between two parallel wires carrying currents has been used to define
20.
An electric iron draws a current of 4 A when connected to a 220 V mains. Its resistance must be
