1.
It is a common notion that the earth's magnetism is due to the
2.
By inserting a soft iron piece into a solenoid, the strength of the magnetic field
3.
A compass needle just above a wire in which electrons are moving towards east, will point
4.
The unit of magnetic flux is
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
6.
A magnetic field cannot exert any force on a
7.
Choose the correct statement:
8.
A magnetic field can exert force on a
9.
The resistance of a conductor is reduced to half its initial value. In doing so the heating effects in the conductor will become
10.
If current in the core decreases, the strength of the magnetic field
11.
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
12.
The unit of induced emf is
13.
The force between two parallel wires carrying currents has been used to define
15.
Fleming's right hand rule gives
16.
Ampere rule is used to find the
17.
By increasing the number of turns in the coil, the strength of the magnetic field
18.
The fact that current is associated with a magnetic field was discovered by
20.
An electric iron draws a current of 4 A when connected to a 220 V mains. Its resistance must be