CBSE
Multiple Choice QuestionsThe earth's magnetic induction at a certain point is 7 x 10-5 Wb/m2. This is to be annuled by the magnetic induction at the centre of a circular conducting loop of radius 5 cm. The required current in the loop is
0.56 A
5.6 A
0.28 A
2.8 A
A narrow beam of protons and deuterons, each having the same momentum, enters a region of uniform magnetic field directed perpendicular to their direction of momentum. The ratio of the radii of the circular paths described by them is
2 : 5
3 : 2
2 : 3
1 : 1
Two particles A and B of masses m and 2m have charges q and 2q respectively. Both particles moving with velocities v1 and v2 respectively in the same direction and enter the same magnetic field B acting normally to their direction of motion. If the two forces FA and FB acting on them are in the ratio of 1 : 2, the ratio of their velocities is
2 : 1
3 : 2
2 : 3
1 : 1
The sensitiveness of a moving coil galvanometer can be increased by decreasing the
number of turns in the coils
area of the coil
magnetic field
couple per unit twist of the suspension
A wire carrying current i and other carrying is in the same direction produce a magnetic field B at the midpoint. What will be the field when 2i current is switched off ?
B/2
2B
B
4B
A horizontal overhead power line carries a current of 90 A in east to west direction. The magnitude and direction of the magnetic field due to the current 1.5 m below the line is
2.5 x 10-5 T towards north
3 x 10-5 T towards east
1.2 x 10-5 T towards south
1 x 10-5 T towards west
An electron is moving with velocity v in the direction of magnetic field B, then force acting on electron is
zero
e (v x B)
e (B x v)
200 J
Susceptibility of a magnetic field is
A galvanometer has a resistance of 30 Q. It gives full scale deflection with a current of 2mA. Calculate, the value of the resistance needed to convert it into an ammeter of range 0 − 0.3 A. The value of the resistance needed to convert galvanometer into ammeter
0.2 Ω
0.3 Ω
0.4 Ω
0.52 Ω
A particle of mass M and charge Q moving with velocity describes a circular path of radius R when subjected to a uniform transverse magnetic field of induction B. The work done by the field when the particle completes one full circle is.
zero
BQ 2R
BQv 2R
