The magnetic moment of a short bar magnet is 4 Am2 . The magnetic induction at a point 10 cm away from its mid point on axial line is B1 , and on the equatorial line is B2 , then
B1 = 8 × 10-4 T , B2 = 4 × 10-4 T
B1 = 2 × 10-4 T , B2 = 1 × 10-4 T
B1 = 10 × 10-4 T , B2 = 5 × 10-4 T
B1 = 6 × 10-4 T , B2 = 3 × 10-4 T
An electromagnetic wave travels along Z- axis. The pair of space and time varying field is
Ey, Bx
By, Ez
Ex, By
Ez, Bx
C.
Ex, By
The vectors E,B and K are mutually perpendicular to each other.
The ratio of inductive reactance to capacitive reactance in an AC circuit will be
ω LC
ω2 L
zero
ω2 LC
The magnetic flux through a circuit of resistance R changes by Δ in times Δt. Then, the-total amount of electric charge that passes in any point in the circuit during this time 'Δt' will be
The value of angle of dip is zero at the magnetic equator because on it
V and H are equal
the value of V is zero
the value of H is zero
the value of V is infinity
In a step up transformer, the turns ratio of field is primary and secondary is 1 : 4. A leclanche cell of emf 1.5 V is connected across the primary. The voltage developed across the secondary will be
3 V
6 V
1 V
zero
A thermister is dipped in a water bath. As the temperature increases the current in the thermistor also increases. This is due to decrease in
resistivity
conductivity
reactance
capacitance
In an AC circuit, voltage and current are given by V = 50 sin (lO0 t) V and I = 50 sin A. The power dissipiated in the circuit is
125 W
625 W
1250 W
100 W
The magnetic flux in a closed circuit of resistance 10 Ω varies with time t (in second) as = (4t2 − 5t + 1)Wb. The magnitude of induced current at t = 0.20 s is
0.12 A
0.38 A
0.34 A
0.12 A