IB Physics HL D 4 2 Hl Faradays Law Questions

Apply Faraday’s law to changing magnetic flux, induced emf, current graphs, moving coils, transformers and electromagnetic induction.

Exam points

state and apply Faraday’s law to calculate induced emf from the number of turns and rate of change of magnetic flux or flux linkage
interpret flux-time and emf-time graphs and explain how field, area, orientation, turns, motion and rotation affect induced emf
analyse induction in moving loops, oscillating magnets, transformers and mutual-induction systems using Lenz’s law, energy transfer, resistance and flux leakage

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Study D.4.2 (HL)—Faraday’s law conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 5]

A rod, R , lies perpendicular to a uniform magnetic field B of strength 0.50 T directed into the plane of the page. R is connected to a circuit and the electric current $I_{\mathrm{R}}$ is 2.0 A .

(a)

A small coil of wire of radius 2.0 cm and 20 turns is now located with its centre 10.0 cm from R. The current in R is kept constant at 2.0 A .

[ 5 ]

(i)

Explain why there is no current induced in the coil.

[ 2 ]

the magnetic field produced by the wire $/ \mathrm{I}_{\mathrm{R}}$ is constant.

therefore the «magnetic» flux/field through the coil is constant.

(ii)

The current in R increases at a constant rate from 2.0 A to 10.0 A in 0.5 seconds.

Calculate the emf induced in the coil.

[ 3 ]

$\begin{aligned} \Delta \mathrm{B}=\frac{\mu_{0}}{2 \pi}\left(\frac{10-2}{0.1}\right) \text { OR } 2 \times 10^{-5}-4 \times 10^{-6}=1.6 \times 10^{-5}<\mathrm{T} \gg \Delta \phi=A \Delta \mathrm{~B}=(\pi)\left(0.02^{2}\right)\left(\left(2 \times 10^{-5}\right)-\left(4 x 10^{-6}\right)\right)=2.5 \times 10^{-8}-5.03 \times 10^{-9} =2.01 \times 10^{-8}<\mathrm{Wb}> \varepsilon=\frac{n \Delta \phi}{\Delta t}=\frac{(20)\left(2.01 \times 10^{-8}\right)}{0.5}=8.0 \times 10^{-7}<\mathrm{V} \gg \end{aligned}$

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IB Physics HL D 4 2 Hl Faradays Law Questions question 1

Question (a)

Question (i)

Question (ii)