Electromagnetic Induction (AQA A Level Physics)

When a coil of wire is rotating in a magnetic field, the e.m.f. induced in the coil does not depend on:

The graph below shows how the magnetic flux Φ linking a coil varies with time t:

Which of the following correctly shows the corresponding induced e.m.f. ϵ in the coil, with respect to time t?  

A nickel ring is dropped over a bar magnet as shown in the image below:

Which of the following statements about the induced current in the ring is correct? 

A section of wire PQ, of length 25 cm, lies perpendicularly across a uniform magnetic field set up between the poles of two bar magnets, as shown in the image below:

The flux density of the magnetic field between the poles is 10 mT. A student lifts the wire vertically upward through the magnetic field at a speed of 0.2 m s^­–1, inducing a current in the wire (the complete circuit is not shown).

If the resistance in the wire is 2 Ω, what is the magnitude of the induced current? 

A rectangular coil is in a uniform magnetic field, which is directed perpendicularly to the coil area and out of the page, as shown in the diagram:

When the coil is rotated about an axis AB at a constant frequency f = 10 revolutions per second, an alternating e.m.f. of peak value  = 1.3 V is induced in it.

What is the maximum value of the magnetic flux linkage through the coil?

A copper ring is suspended by a long, light rod pivoted at X so that it may swing as a pendulum, as shown in the diagram below:

An electromagnet is set up so that the ring can pass over it as it swings. The ring is then set into oscillation at time t = 0, with switch K open. It completes two full oscillations, at which point the switch K is closed at time t = .

Which graph correctly shows the variation of the displacement  with time t?

A bar magnet moves steadily from right to left through a very long solenoid as shown in the diagram below.

A galvanometer is connected across the solenoid. A galvanometer measures the amount of current (and voltage) through a moving coil, shown by a deflecting needle.

Which graph shows the deflection of the galvanometer, θ with time, t?

The south pole of a bar magnet is pushed into one end of a coil of wire, which is connected to a sensitive galvanometer as shown:

A galvanometer measures the amount of current through a moving coil, shown by a deflecting needle.

A maximum deflection of the galvanometer needle of 7 units to the left is observed. 

Next, the north pole of the magnet is pushed from the outside back into the other end of the coil at twice the speed.

What would the maximum deflection of the galvanometer needle be?

An oscillating magnetic field, B, is applied perpendicular to the plane of a small flat coil of copper wire.

 The equation for the changing flux density is given by:

B = sin (ωt)

where  is the amplitude and ω is the angular frequency of the oscillating magnetic field.

 If the period of the oscillating magnetic field is T, at what time t, is the magnitude of the induced e.m.f in the coil a maximum?