Grade 11 Physical Sciences · Electricity and Magnetism

Calculate magnetic flux and induced emf

Calculate magnetic flux with Φ = BA cos θ, or the induced emf with emf = −NΔΦ/Δt for a coil.

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Electromagnetism grade 11 Lesson 3: Magnetic Flux CalculationKevinmathscience

Electromagnetism grade 11 Lesson 4: Faradays LawKevinmathscience

Grade 11 Electromagnetism calculations: Calculating magnetic flux and induced emfMiss Martins Maths and Science

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Question WE3 · Siyavula Grade 11 Physical Sciences, 10.3 Faraday's law of electromagnetic induction, Worked example 3 · 3 marks

WE3 Consider a circular coil of

4

turns with radius

3 \times 1 0^{- 2}

m. The solenoid is subjected to a varying magnetic field that changes uniformly from

0, 4

T to

3, 4

T in an interval of

27

s. The axis of the solenoid makes an angle of

35°

to the magnetic field. Find the induced emf.(3)

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More past paper questions: calculate magnetic flux and induced emf

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3. Question 8.3.3 · November 2025 · Paper 1 · Provincial · 3 marks
The north pole of a magnet is pushed into a solenoid as shown in the diagram below.
8.3 A coil with $350$ turns has an area of $0, 08$ m $^{2}$ . It is held with its axis coinciding with the direction of a magnetic field of strength $0, 6$ T. In order to induce an emf in the coil, it is pulled out of the magnetic field in $0, 25$ seconds.

Answer the following questions.
8.3.3 Calculate the magnetic flux linkage.(3)
Show the memo (3 ticks)Memo
1. ✓
  Formula $Φ = B A cos θ$
  1 mark · Calculate magnetic flux and induced emf
2. ✓
  Substitution $Φ = 0, 6 (0, 08) cos 0°$
  1 mark · Calculate magnetic flux and induced emf
3. ✓
  Answer with unit $Φ = 0, 048$ Wb
  1 mark · Calculate magnetic flux and induced emf
4. Question WE1 · Siyavula Grade 11 Physical Sciences, 10.3 Faraday's law of electromagnetic induction, Worked example 1 · 4 marks
WE1 Consider a flat square coil with $5$ turns. The coil is $0, 50$ m on each side and has a magnetic field of $0, 5$ T passing through it. The plane of the coil is perpendicular to the magnetic field: the field points out of the page. Use Faraday's Law to calculate the induced emf, if the magnetic field increases uniformly from $0, 5$ T to $1$ T in $10$ s. Determine the direction of the induced current.(4)
Show the memo (4 ticks)Memo
1. ✓
  Faraday's law with flux $E = - N \frac{Δ ϕ}{Δ t}$
  The field is perpendicular to the coil (along the normal), so $ϕ = B A$ .
  $E = N \frac{A ( B _{f} - B _{i} )}{Δ t}$ (magnitude)
  1 mark · Calculate magnetic flux and induced emf
2. ✓
  Substitution $E = (5) \frac{( 0 , 50 ) ^{2} ( 1 - 0 , 50 )}{10}$
  1 mark · Calculate magnetic flux and induced emf
3. ✓
  Answer with unit $E = 0, 0625$ V
  1 mark · Calculate magnetic flux and induced emf
4. ✓
  Direction of the induced currentThe induced current is anti-clockwise as viewed from the direction of the increasing magnetic field.
  1 mark · Use the right-hand rule

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