Class 12 Moving Charges And Magnetism CBSE Questions & Answers

The magnetic field in a circular loop of diameter 0.1 m carrying a current of 1 A is

Two protons move parallel to each other with equal speeds 3 x 105 ms-1. The ratio of magnetic and electric force between them is

A particle having charge 100 times that of an electron is revolving in a circular path of radius 0.8 m with one rotation per second. Magnetic field produced at the centre of the circular path is

A wire of length L is bent to form a ring of single loop and current is flown through it. The magnetic field at its centre is B. If the same wire is bent to form 2 loops and same current is flowing, the new B’ at its centre will be

In a coil of 0.1 m radius and 100 turns, 0.1 amp current is passed. What will be the magnetic field at the centre of the coil

The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 \(\mu\)T. what will be its value at the centre of the loop?

A circular coil of radius R carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance r from the center of the coil such that \({\rm{r }} > > {\rm{ R}}\), varies as

A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be

In hydrogen atom, the electron is making \({\rm{6}}.{\rm{6 }} \times {\rm{ 1}}{0^{{\rm{15}}}}\) rev./sec around the nucleus in an orbit of radius 0.528 Å .The magnetic moment (\({\rm{A}}{{\rm{m}}^{\rm{2}}}\)) will be

A magnetic needle lying parallel to a magnetic field requires W units of work to turn it, through 600. The torque needed to maintain the needle in this position will be

If number of turns, area and current through a coil is given by n, A and i respectively then its magnetic moment will be

The work done in rotating a magnet of magnetic moment \({\rm{2 A}}-{{\rm{m}}^{\rm{2}}}\) in a magnetic field of \({\rm{5 }} \times {\rm{ 1}}{0^{ - {\rm{3}}}}\) T form the direction along the magnetic field to opposite direction to the magnetic field, is

A magnet of magnetic moment \({\rm{2J}}{{\rm{T}}^{ - {\rm{1}}}}\) is aligned in the direction of magnetic field of 0.1.T. What is the net work done to bring the magnet normal to the magnetic field?

A bar magnet is equivalent to

Two straight horizontal parallel wires are carrying the same current in the same direction, d is the distance between the wires. You are provided with a small freely suspended magnetic needle. At which of the following positions will the orientation of the needle be independent of the magnitude of the current in the wires