Electromagnetism

Question 3

Hard

An experiment is carried out using a search coil placed at the end of a long solenoid connected to an alternating current supply. The plane of the search coil is tilted such that it makes an angle $\theta\,$ with the central axis of the solenoid. The maximum alternating induced electromotive force (e.m.f.) across the ends of the search coil is $E_0$ .

Name an instrument that can be used to determine $E_0$ .

[1]

The equation for $E_0\,$ is:

E_0 = K I_0 A N f \sin \theta

where:

$I_0\,$ is the maximum current in the solenoid
$A\,$ is the cross-sectional area of the search coil
$N\,$ is the number of turns of the search coil
$f\,$ is the frequency of the alternating current
$\times 10^{-3} \text{ V A}^{-1} \text{ m}^{-2} \text{ s}$

The magnitude of the induced e.m.f. can be determined using Faraday's law of electromagnetic induction:

\text{e.m.f.} = \text{rate of change of magnetic flux linkage}

Suggest which quantity, or quantities, in the equation for $E_0\,$ are linked to:

the 'rate' part of the law
the 'change of magnetic flux linkage' part of the law

[2]

A student plots a straight-line graph of $E_0\,$ against $sin⁡θ\sin \theta$ .

Determine the frequency $f$ , including its absolute uncertainty. Write your value of $f\,$ to 2 significant figures.

Given data:

$AI_0 = (6.4 \pm 0.2) \text{ A}$
$\pm 0.1) \times 10^{-5} \text{ m}^2$
$N = 4000$
$V\text{gradient of line} = K I_0 A N f = (0.34 \pm 0.02) \text{ V}$

[5]

Electromagnetism

1 2 3 4 5 6 7 8 9

Question 3

Hard

Name an instrument that can be used to determine $E_0$ .

[1]

The equation for $E_0\,$ is:

E_0 = K I_0 A N f \sin \theta

where:

$I_0\,$ is the maximum current in the solenoid
$A\,$ is the cross-sectional area of the search coil
$N\,$ is the number of turns of the search coil
$f\,$ is the frequency of the alternating current
$\times 10^{-3} \text{ V A}^{-1} \text{ m}^{-2} \text{ s}$

The magnitude of the induced e.m.f. can be determined using Faraday's law of electromagnetic induction:

\text{e.m.f.} = \text{rate of change of magnetic flux linkage}

Suggest which quantity, or quantities, in the equation for $E_0\,$ are linked to:

the 'rate' part of the law
the 'change of magnetic flux linkage' part of the law

[2]

A student plots a straight-line graph of $E_0\,$ against $sin⁡θ\sin \theta$ .

Determine the frequency $f$ , including its absolute uncertainty. Write your value of $f\,$ to 2 significant figures.

Given data:

$AI_0 = (6.4 \pm 0.2) \text{ A}$
$\pm 0.1) \times 10^{-5} \text{ m}^2$
$N = 4000$
$V\text{gradient of line} = K I_0 A N f = (0.34 \pm 0.02) \text{ V}$

[5]

Electromagnetism

Question 3

Electromagnetism Questions

Electromagnetism

Question 3

Electromagnetism Questions