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Question 18M.3.SL.TZ1.2b

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Date May 2018 Marks available [Maximum mark: 3] Reference code 18M.3.SL.TZ1.2b
Level SL Paper 3 Time zone TZ1
Command term Explain Question number b Adapted from N/A
b.
[Maximum mark: 3]
18M.3.SL.TZ1.2b

An experiment to find the internal resistance of a cell of known emf is to be set. The following equipment is available:

M18/4/PHYSI/SP3/ENG/TZ1/02

(b)

It is noticed that the resistor gets warmer. Explain how this would affect the calculated value of the internal resistance.

[3]

Markscheme

resistance of resistor would increase / be greater than 10 Ω

R + r «from ε = I(R + r)» would be overestimated / lower current

therefore calculated r would be larger than real

 

Award MP3 only if at least one previous mark has been awarded.

[3 marks]