Q8 · 2024 · Paper 2Complex unfamiliar7 marks
QUESTION 8 (7 marks)
A U-shaped magnet was placed on a digital scale. A current-carrying wire was connected to a variable power supply and passed through the space between the poles of the magnet. The length of wire within the magnetic field was , and the wire did not touch the magnet.
a)[1 mark]
Sketch the magnetic field between the north and south poles of the magnet when there is no current in the wire.
The power supply was switched on. Readings from the digital scale were recorded while the current in the wire was varied to produce the graph shown.
b)[1 mark]
Identify the mass of the magnet.
c)[5 marks]
Determine the strength of the magnetic field produced by the magnet. Show your working.
WORKED SOLUTION
7 marksQCAA guide · typeset solution
ANSWER
See worked solution below.
Worked solution
Mass of the magnet is equal to the y-intercept of the graph.
Mass = 0.96 kg
Re
Re
sin
sin90
1
Magnetic
Scale
ading
WeightOfMag
Scale
ading
WeightOfMagnet
F
F
F
F
F
BIL
F
BIL
θ
=
=
−
=
=
−
Referring to (3.00,0.971)
T
0.971 9.8
0.960 9.8
3.00
0.
9.52
9.41
0.240
0.449
08
B
B
×
=
−
−
×
=
×
=
×
• sketches arrow/s from north to
south [1 mark]
• identifies the mass of the magnet
[1 mark]
g
• recognises the scenario relates to
magnetic field strength [1 mark]
• recognises sin 90° = 1 [1 mark]
• identifies appropriate data from the
graph [1 mark]
• shows appropriate mathematical
reasoning [1 mark]
• determines the magnetic field
strength [1 mark]
One QCAA sample method typeset for web; criterion wording is adapted from the official marking guide.
How many marks did you earn?
Compare your working with the guide above.