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Question 19N.3.SL.TZ0.a(ii)

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Date November 2019 Marks available [Maximum mark: 3] Reference code 19N.3.SL.TZ0.a(ii)
Level SL Paper 3 Time zone TZ0
Command term Explain Question number a(ii) Adapted from N/A
a(ii).
[Maximum mark: 3]
19N.3.SL.TZ0.a(ii)

The resistance R of a wire of length L can be measured using the circuit shown.

In one experiment the wire has a uniform diameter of d = 0.500 mm. The graph shows data obtained for the variation of R with L.

The gradient of the line of best fit is 6.30 Ω m–1.

Explain, by reference to the power dissipated in the wire, the advantage of the fixed resistor connected in series with the wire for the measurement of R.

[3]

Markscheme

measurement should be performed at a constant temperature
OR
resistance of wire changes with temperature ✔

series resistance prevents the wire from overheating
OR
reduces power dissipated in the wire ✔

by reducing voltage across/current through the wire ✔

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