DP Physics (last assessment 2024)

Question 21M.2.SL.TZ2.a

Date	May 2021	Marks available	[Maximum mark: 2]	Reference code	21M.2.SL.TZ2.a
Level	SL	Paper	2	Time zone	TZ2
Command term	Demonstrate	Question number	a	Adapted from	N/A

[Maximum mark: 2]

21M.2.SL.TZ2.a

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 charge per unit area on the surface of the wall is σ. It can be shown that the electric field strength E due to the charge on the wall is given by the equation

$E = \frac{σ}{2 ε_{0}}$ .

Demonstrate that the units of the quantities in this equation are consistent.

[2]

Markscheme

identifies units of $σ$ as ${C m}^{- 2}$ ✓

$\frac{C}{m^{2}} \times \frac{N m^{2}}{C^{2}}$ seen and reduced to ${N C}^{- 1}$ ✓

Accept any analysis (eg dimensional) that yields answer correctly

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Core

Core » Topic 1: Measurements and uncertainties » 1.1 – Measurements in physics

Core » Topic 1: Measurements and uncertainties

Question 21M.2.SL.TZ2.a

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