Physics 9702 · AS & A Level · Electromagnetic induction

Electromagnetic induction — practice question

A uniform magnetic field with flux density $B$ is inclined at an angle $\theta$ to the flat plane PQRS, as illustrated in Fig. 5.1. The area of plane PQRS is $A$.
(a)

State that:

(a(i))[1]

what the term magnetic field means,

(a(ii))[1]

an expression for the magnetic flux $\Phi$ through plane PQRS, written in terms of $A$, $B$ and $\theta$.

(b)

A vertical aluminium window frame DEFG is $52\,\text{cm}$ wide and $95\,\text{cm}$ long, as shown in Fig. 5.2. It is hinged along the vertical edge DG. The Earth's horizontal magnetic-field component $B_H$ is $1.8 \times 10^{-5}\,\text{T}$. When the window is closed, the frame is normal to the horizontal component $B_H$. The window is then opened so that the plane of the window turns through $90^\circ$.

(b(i))[1]

Explain why opening the window produces no change in magnetic flux linkage from the vertical component of the Earth’s magnetic field.

(b(ii))[2]

Calculate the change in magnetic flux linkage when the window opens through $90^\circ$.

(c)
(c(i))[2]

State Faraday’s law of electromagnetic induction briefly.

(c(ii))[1]

The window in (b) is opened in $0.30\,\text{s}$. Use your answer to (b)(ii) to work out the average e.m.f. induced in the window frame.

(c(iii))[1]

State which sides of the window frame have the e.m.f. induced between them.

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