DP Physics (last assessment 2024)

Question 21M.2.HL.TZ2.d.i

Date	May 2021	Marks available	[Maximum mark: 3]	Reference code	21M.2.HL.TZ2.d.i
Level	HL	Paper	2	Time zone	TZ2
Command term	Calculate	Question number	d.i	Adapted from	N/A

d.i.

[Maximum mark: 3]

21M.2.HL.TZ2.d.i

A vertical wall carries a uniform positive charge on its surface. This produces a uniform horizontal electric field perpendicular to the wall. A small, positively-charged ball is suspended in equilibrium from the vertical wall by a thread of negligible mass.

The centre of the ball, still carrying a charge of 1.2 × 10⁻⁶C, is now placed 0.40 m from a point charge Q. The charge on the ball acts as a point charge at the centre of the ball.

P is the point on the line joining the charges where the electric field strength is zero. The distance PQ is 0.22 m.

Calculate the charge on Q. State your answer to an appropriate number of significant figures.

[3]

Markscheme

$\frac{Q}{0 . 22^{2}} = \frac{1.2 \times 10^{- 6}}{0 . 18^{2}}$ ✓

$« + » 1.8 \times 10^{- 6} « C »$ ✓

2sf ✓

Do not award MP2 if charge is negative

Any answer given to 2 sig figs scores MP3

Syllabus sections

Core

Core » Topic 5: Electricity and magnetism » 5.1 – Electric fields

Core » Topic 5: Electricity and magnetism

Question 21M.2.HL.TZ2.d.i

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