Current is flowing in a coil of area A and number of turns N, then magnetic moment of the coil, M is equal to
NiA
Ni/A
N2Ai
A galvanometer of resistance 50 Ω is connected to a battery of 3 V along with a resistance of 2950 Ω in series. A full scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be
5050 Ω
5550 Ω
6050 Ω
4450 Ω
Two equal electric currents are flowing perpendicular to each other as shown in the figure. AB and CD are perpendicular to each other and symmetrically placed with respect to the currents, where do we expect the resultant magnetic field to be zero?
On AB
On CD
On both AB and CD
On both OD and BO
A straight wire of diameter 0.5 mm carrying a current of 1 A is replaced by another wire of 1 mm diameter carrying same current. The strength of magnetic field far away is
twice the earlier value
same as the earlier value
one – half of the earlier value
one quarter of the earlier value
The total charge induced in a conducting loop when it is moved in magnetic field depends on
the rate of change of magnetic flux
initial magnetic flux only
the total change in magnetic flux
final magnetic flux only
The magnetic induction at a point P which is at the distance of 4 cm from a long current carrying wire is 10-3 T. The field of induction at a distance 12 cm from the current will be
3.33 × 10-4 T
1.11 × 10-4 T
3 × 10-3 T
9 × 10-3T
A 10 eV electron is circulating in a plane at right angles to a uniform field of magnetic induction 10-4 Wb/m2 ( =1.0 gauss). The orbital radius of the electron is
12 cm
16 cm
11 cm
18 cm
The magnetic field at a distance r from a long wire carrying current I is 0.4 T. The magnetic field at a distance 2r is
0.2 T
0.8 T
0.1 T
1.6 T
torque is formed
emf is induced
Both (a ) and ( b ) are correct
None of the above
A deutron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 m in a plane perpendicular to magnetic field B. The kinetic energy of the proton that describes a circular orbit of radius 0.5 m in the same plane with the same B is
25 keV
50 keV
200 keV
100 keV
