DP Physics (first assessment 2025)

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Question EXE.2.SL.TZ0.16

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Date Example questions Example questions Marks available [Maximum mark: 7] Reference code EXE.2.SL.TZ0.16
Level SL Paper 2 Time zone TZ0
Command term Determine, Discuss Question number 16 Adapted from N/A
16.
[Maximum mark: 7]
EXE.2.SL.TZ0.16

Two parallel conducting wires both of length 0.25 m are arranged 0.20 m apart in a circuit. The resistance of one wire is 15 Ω and the resistance of the other wire is 30 Ω. The current in the 15 Ω wire is 10 A.

Assume that the magnetic force due to the Earth can be ignored.

(a)

Determine the magnetic force acting on the 15 Ω wire due to the current in the 30 Ω wire.

[4]

Markscheme

Use of combination of resistors OR V=IR ✓

To show that current in 30 Ω wire is 5.0 A ✓ 

FI=2×10-7I15I30r=2×10-7×10×50.20 ✓

F=5×10-5×0.25= 1.3×10-5 N ✓ 

(b)

The magnetic field strength of Earth’s field at the location of the wires is 45 μT.

Discuss the assumption made in this question.

[3]

Markscheme

Use of F=BIl ✓

45×10-6×10×0.25=1.15×10-4 N ✓

Concludes that the assumption is not valid ✓

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