DP Physics (last assessment 2024)

Question 21M.2.HL.TZ2.a.ii

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

a.ii.

[Maximum mark: 2]

21M.2.HL.TZ2.a.ii

The primary coil of a transformer is connected to a 110 V alternating current (ac) supply. The secondary coil of the transformer is connected to a 15 V garden lighting system that consists of 8 lamps connected in parallel. Each lamp is rated at 35 W when working at its normal brightness. Root mean square (rms) values are used throughout this question.

Determine the total resistance of the lamps when they are working normally.

[2]

Markscheme

ALTERNATIVE 1

calculates total current $= \frac{35}{15} \times 8 « = 18.7 A »$ ✓

resistance $= « \frac{15}{18.7} = » 0.80 « Ω »$ ✓