The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux Φ linked with the primary coil is given by Φ = Φ0 + 4t, where Φ is in weber, t is time in second and Φ0 is a constant, the output voltage across the secondary coil is
90 V
120 V
220 V
30 V
An alternating voltage E = 200 sin 300 t is applied across a series combination of R = 10 Ω and an inductor 800 mH. The power factor of the circuit is
0.022
0. 065
0.042
0. 084
Energy needed to establish an alternating current I in a coil of self inductance L is
L di/dt
Zero
LI2/2
IL2/2
A magnet is allowed to fall through a metallic ring. During fall, its acceleration is
less than g
equal to g
equal to 2g
greater than g
A current varying at the rate of 3A/s in a coil generates an e.m.f. of 8mV in a nearby coil. The mutual inductance of hte two coils is
2.66 H
2.66 x 10-3 mH
0.266 H
2.66 mH
The time constant of C - R circuit is
1/CR
C/R
CR
R/C
Two circuits have mutual inductance of 0.09 H. Average e.m.f. induced in the secondary by a change of current from 0 to 20 A in 0.006 second in the primary will be
300 V
200 V
180 V
Two coils have a mutual inductance of 0.005 H. The current changes in the first coil according to the equation I = I0 sin ωt where I0 = 10A and ω = 100π rad/sec. The maximum value of e.m.f. in the second coil is
5π volts
2π volts
π volts
4π volts
During a current change from 2 A to 4 A in 0.05 second, 8 V of e.m.f. is developed in the coil. The coefficient of self induction is
0.1 H
0. 4H
0. 8
0. 2 H
In an experiment, 200 V AC is applied at the ends of an LCR circuit. The circuit consists of an inductive reactance (XL) = 50 Ω, capacitive reactance (XC) = 50 Ω and ohmic resistance (R) = 10 Ω. The impedance of the circuit is
10 Ω
20 Ω
30 Ω
40 Ω
