Electromagnetic...

The current in a LR circuit builds up to 3/4th of its steady state value in 4s. The time constant of this circuit is

A simple pendulum with bob of mass m and conducting wire of length L swings under gravity through an angle 2 θ. The earth\'s magnetic field component in the direction perpendicular to swing is B. Maximum potential difference induced across the pendulum is

An inductor (L = 100 mH), a resistor (R = 100 Ω) and a battery (E = 100V) are initially connected in series as shown in the figure. After a long time the battery is disconnected after short circuiting the points A and B. The current in the circuit 1 ms after the short circuit is

A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating, it is very difficult to stop. But if an aluminum plate is placed near to the coil, it stops. This is due to

The graph shows the variation in magnetic flux ɸ(t) with time through a coil. Which of the statements given below is not correct

The variation of induced e.m.f. (E) with time (t) in a coil if a short bar magnet is moved along its axis with a constant velocity is best represented as

The current through a 4.6 H inductor is shown in the following graph. The induced e.m.f. during the time interval t = 5 milli-sec to 6 milli-sec will be

An alternating current of frequency 200 rad/sec and peak value 1A as shown in the figure, is applied to the primary of a transformer. If the coefficient of mutual induction between the primary and the secondary is 1.5 H, the voltage induced in the secondary will be

A horizontal loop abcd is moved across the pole pieces of a magnet as shown in fig. with a constant speed v. When the edge ab of the loop enters the pole pieces at time t = 0 sec, which one of the following graphs represents correctly the induced e.m.f. in the coil

Some magnetic flux is changed from a coil of resistance 10 ohm. As a result an induced current is developed in it, which varies with time as shown in figure. The magnitude of change in flux through the coil in webers is