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Question 20N.2.HL.TZ0.c(ii)

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Date November 2020 Marks available [Maximum mark: 2] Reference code 20N.2.HL.TZ0.c(ii)
Level HL Paper 2 Time zone TZ0
Command term Determine Question number c(ii) Adapted from N/A
c(ii).
[Maximum mark: 2]
20N.2.HL.TZ0.c(ii)

The diagram shows the electric field lines of a positively charged conducting sphere of radius R and charge Q.

Points A and B are located on the same field line.

A proton is placed at A and released from rest. The magnitude of the work done by the electric field in moving the proton from A to B is 1.7×10-16J. Point A is at a distance of 5.0×10-2m from the centre of the sphere. Point B is at a distance of 1.0×10-1m from the centre of the sphere.

Determine the charge Q of the sphere.

[2]

Markscheme

8.99×109×Q×15.0×10-2-11.0×10-1=1.1×103 ✓


Q=1.2×10-8«C» ✓

Examiners report

Even though many were able to choose the appropriate formula from the data booklet they were often hampered in their use of the formula by incorrect techniques when using fractions.