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2 marksAlternating Currents

CAPE Physics Unit 2 · 2008 (Rest of Region) · Paper 2 · Question 4(c)(ii)b)

Figure 5 shows a circular coil of 150 turns and diameter 0.1 m rotating 25 times per second in a uniform magnetic field of 4.0 \times 10^{-4}\text{ T}. At t=0 the coil is aligned as shown.

Find the r.m.s. value of the e.m.f. induced in the coil.

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Other parts of this question

  1. 4(a)Define magnetic flux and state Lenz's law.[2 marks]
  2. 4(b)(i)Explain why the ring jumps into the air.[2 marks]
  3. 4(b)(ii)Describe and explain the motion of the ring, if any, when a slot is cut into the ring as shown in Figure 4(b).[2 marks]
  4. 4(c)(i)Calculate the total magnetic flux \Phi through the coil at time t = 0.[2 marks]
  5. 4(c)(ii)a)Given the rate of change of flux is 2\pi f \Phi \sin(2\pi f t), find the maximum instantaneous value of the induced e.m.f. in the coil.[3 marks]
  6. 4(c)(iii)State what difference it would make to the induced e.m.f. if the coil were fixed and the magnet rotated at the same rate and in the same direction.[2 marks]

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