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2 marksMagnetic Forces

CAPE Physics Unit 2 · 2012 · Paper 2 · Question 1(a)(i)

A current balance apparatus is used to find the magnetic field between the poles of a permanent magnet, where downward magnetic force on a wire is balanced by the torque from a movable slider's weight.

Mark on Figure 1 the direction of current in wire AB and state the name of the rule used to determine this direction.

This question uses a figure or table from the paper — you'll see it when you practise.

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Other parts of this question

  1. 1(a)(ii)Show, on the provided diagram of poles N and S with wire AB, the magnetic field lines when current flows in AB.[1 mark]
  2. 1(b)(i)Show that at equilibrium, the current through the circuit is given by I = mgx / (BLy), where L is the length of wire AB.[3 marks]
  3. 1(b)(ii)Describe how the apparatus is used to obtain a set of readings for I and x, stating clearly how results are taken.[3 marks]
  4. 1(c)(i)Draw the best straight line through the data plotted in Figure 2.[1 mark]
  5. 1(c)(ii)Determine the gradient of the best line drawn on Figure 2.[2 marks]
  6. 1(c)(iii)Given that y = 2.0 cm, L = 5.0 cm, and m = 0.50 g, calculate the magnetic flux density, B, of the magnet.[3 marks]

More practice: the rest of this paper · more Magnetic Forces questions · all CAPE Physics Unit 2 past papers