A square wire frame is placed perpendicularly in the region of a uniform magnetic field of flux density B = 0.5 T, as shown in the diagram below.
What is the magnetic flux through the square wire frame?
0 Wb
0.005 T
50 Wb
0.005 Wb
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Which statement about magnetic flux linkage is incorrect?
Flux linkage is the product of the magnetic flux and the number of turns in a coil
The standard unit of magnetic flux linkage is Tesla (T)
The flux linkage through a coil of wire is maximum when the angle between the flux and the coil’s normal line is 0º
An e.m.f. is induced in a coil of wire when the flux linkage changes
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The magnetic flux through a coil of 100 turns changes from 2 × 10–3 Wb to zero in 0.4 s.
What is the average induced e.m.f. in the coil?
0 V
0.5 V
5 V
500 V
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The diagram below shows a vertical square wire frame whose area starts at right angles to a horizontal and uniform magnetic field B.
The wire frame can rotate about the vertical axis shown.
Which statement best describes the change in magnetic flux linkage as the wire frame rotates through an angle of 90º?
Maximum to zero
Zero to maximum
Maximum to maximum
No change in magnetic flux linkage
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Which of the following units are valid when measuring the change in magnetic flux linkage?
Volts
Volt seconds
Metres
Tesla
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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?
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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?
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A coil with 100 turns and an area of 0.30 m2 is set up inside a uniform magnetic field, of magnitude 62 mT, as shown in the image below.
When the coil spins at a constant rate about the rotation axis, an alternating e.m.f ϵ is induced as shown in the image below:
The magnitude of the induced e.m.f ϵ can be calculated at any time t using the equation:
= X sin (Y t)
Which line, A to D in the table below correctly identifies the value of X and Y?
| X | Y | |
| A | 1.9 | 6.2 |
| B | 5.8 | 3.1 |
| C | 1.9 | 3.1 |
| D | 5.8 | 6.2 |
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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?
Less than 7 units to the right
Less than 7 units to the left
More than 7 units to the left
More than 7 units to the right
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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?
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When a coil of wire is rotating in a magnetic field, the e.m.f. induced in the coil does not depend on:
The angular velocity of the coil
The resistance of the coil
The magnetic flux density
The number of turns of the coil
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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?
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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?
The induced current flows in a clockwise direction
The induced current flows in an anticlockwise direction
The induced current flows in a clockwise direction and then in an anticlockwise direction
The induced current flows in an anticlockwise direction and then in a clockwise direction
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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?
0.25 mA
0.5 mA
0.25 A
5 A
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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?
0.13 Wb turns
0.041 Wb turns
0.021 Wb turns
0.21 Wb turns
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