An alternating current of the r.m.s value of 4.0 A and frequency 50Hz flows in a circuit containing a 10Ω resistor. The peak current is then ?
A. 20A
B. 20.66A
C. 6.66A
D. 5.66A
Physics
The value of the steady current which when flowing through the same resistor produces heat at the same rate as the mean rate of heat produced by the alternating current is
A. Average current
B. Sinusoidal current
C. r.m.s current
D. Net current
Waves emitted from the antenna are
A. Sound waves
B. Electromagnetic waves
C. Radio waves
D. Modulated waves
Waves emitted from the antenna are Read More »
An electromagnetic wave consists of
A. Electric and magnetic fields moving parallel to each other
B. Magnetic field moving with velocity of light in space
C. Electric field moving with velocity of light
D. Electric and magnetic fields moving perpendicular to each other
An electromagnetic wave consists of Read More »
Electromagnetic waves travel in free space with the speed of
A. λ-rays
B. Positive rays
C. Cathode rays
D. More than sound waves
Electromagnetic waves travel in free space with the speed of Read More »
An alternating current or voltage
A. fluctuates off and on
B. varies in magnitude alone
C. changes its direction again and again
D. changes its magnitude harmonically and reverses its direction of flow after regularly recurring intervals
An alternating current or voltage Read More »
A moving coil galvanometer of resistance 100? gives half scale deflection for a current of 20mA. What will be the potential difference across it ?
A. 4 volt
B. 5 volt
C. 2 volt
D. 0.4 volt
Heating a magnet will
A. weaken it
B. strengthen it
C. reverse its polarity
D. demagnetize it completely
Heating a magnet will Read More »
Galvanometer is a very sensitive device with
A. very low damping
B. very high damping
C. no damping at all
D. radial field disintegration
Galvanometer is a very sensitive device with Read More »