A circular disc of radius 0.2 metre is placed in a uniform magnetic field of induction 1/π (Wb)/(m²) in such a way that its axis makes an angle of 60° with ⃗B. The magnetic flux linked with the disc is

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(3) 0.02 Wb. φ=BA cos θ, where θ is the angle between ⃗B and the normal to the disc. The axis of the disc is itself the normal to the disc, so θ=60° and cos θ=1/2. A=π r²=π×(0.2)²=0.04π m². φ=1/π×0.04π×1/2=0.04×1/2=0.02 Wb. The π in the field was chosen to cancel the π in the area.

A circular disc of radius 0.2 metre is placed in a uniform magnetic field of induction 1/π (Wb)/(m²) in such a way that its axis makes an angle of 60° with ⃗B. The magnetic flux linked with the disc is

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