Q8 · 2023 · Paper 2Complex familiar6 marks
QUESTION 8 (6 marks)
A length of wire, AB, is placed across an incomplete loop sitting within a magnetic field as shown. Wire AB then moves with a constant velocity of , creating an induced EMF of .
a)[4 marks]
Determine the magnitude of the magnetic field strength experienced by the loop. Show your working. Give your answer to two significant figures.
b)[2 marks]
Draw a conclusion about the direction of the induced current within the loop. Justify your reasoning.
WORKED SOLUTION
6 marksQCAA guide · typeset solution
ANSWER
See worked solution below.
Worked solution
Sample response The
The induced current is a result of the changing area of the ere
enclosed loop. la
AA = Alw= wvAt eid
Therefore:
A(BA
emf = 9 ABA) i
At ° de
t
BwvAt s
emf =—|1x———
wf At
23x10° =—Bx1.4x40
23x10°
B=—_
14x40
=4.1x107 T
Magnetic field strength = 4.1x107’ T (to two significant figures)
The induced current in the loop moves in an anticlockwise * cc
direction. This is because the induced current will oppose any in
change as described by Lenz’s law. « ju
(1
he response:
e recognises the scenario relates to Faraday’s
law and changing area [1 mark]
• identifies relationship for the change in area
over time [1 mark]
• provides appropriate mathematical reasoning
[1 mark]
• determines the magnitude of the magnetic field
strength [1 mark]
e concludes the direction of the induced current
in the loop is anticlockwise [1 mark]
e justifies the conclusion using Lenz’s law
[1 mark]
One QCAA sample method typeset for web; criterion wording is adapted from the official marking guide.
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Compare your working with the guide above.