An AC supply gives 30 Vrms which passes through a 10 Ω resistance. The power dissipated in it is
90 √2 W
90 W
45√2 W
45 W
A coil of resistance R and inductance L is connected to a battery of e.m.f. E volts. The final current in the coil is
A 100 mH coil carries a current of 1 A. Energy stored in the magnetic field is
0.5 J
I J
0.1 J
0.05 J
A magnetic field of 2 x 10-2 T acts at right angles to a coil of area 100 cm2 with 50 turns. The average e.m.f. induced in the coil is 0.1 V when it is removed from the field in t sec. The value of t is
0.1 s
10 s
0.01 s
1s
In an AC circuit, the rms value of current, irms is related to the peak current, i0 by the relation
irms = √2i0
irms = πi0
irms = i0/π
irms = 1/√2 i0
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
120 V
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
The time constant of C - R circuit is
1/CR
C/R
CR
R/C
Two inductors each of inductance L are connected in parallel. What is their equivalent inductance?
2L
L
L/2
L/4
If a current is passed through a spring, then the spring
expands
gets compressed
remains same
None of these
