The Physics Question Bank

Electromagnetic Induction (A level)

✏️ Paper first! Work out every question on paper before you open the answer. Write down every step – the equation, the numbers with units, the rearranging and the answer with its unit. In the exam, if your final answer is wrong you can still get marks for correct working, but only if the examiner can see it.

← All A level physics practice tools

For A level physics (AQA, OCR A and Edexcel). Watch a magnet fall through a coil and a coil rotate in a field, with live flux-linkage and emf graphs. Then practise flux and Faraday’s law, Lenz’s law, ε = Blv, reading the graphs, transformers and rms values.

Topic
0correct 0attempted 0streak

Worked solution

    Key facts

    Φ = BA    flux linkage NΦ = BAN cos θ

    Φ is in webers (Wb); flux linkage is in Wb turns. θ is the angle between the field and the normal to the coil.

    ε = N ΔΦ/Δt    (the gradient of the NΦ–t graph)

    Lenz’s law: the induced current flows so as to oppose the change that produces it. This follows from conservation of energy.

    rod moving through a field: ε = Blv

    rotating coil: ε = BANω sin ωt    ω = 2πf = 2π/T

    The emf is 90° (a quarter of a cycle) out of phase with the flux linkage. Doubling ω doubles both the peak emf and the frequency.

    Ns/Np = Vs/Vp    efficiency = IsVs / IpVp

    Laminated soft-iron cores reduce eddy currents, so less energy is wasted heating the core.

    Vrms = V0/√2    Irms = I0/√2

    Calculated answers within 2% are marked correct. Values read from a graph or oscilloscope are marked correct within about 3–4% (or a third of a small square).

    ← All A level physics practice tools

    How useful was this page?

    Click on a star to rate it!

    Average rating 0 / 5. Vote count: 0

    No votes so far! Be the first to rate this post.

    📣 Share this page with your class

    WhatsAppFacebookXEmail