DP Physics (last assessment 2024)

Question 21M.2.HL.TZ1.5c.iii

Date	May 2021	Marks available	[Maximum mark: 2]	Reference code	21M.2.HL.TZ1.5c.iii
Level	HL	Paper	2	Time zone	TZ1
Command term	Determine	Question number	c.iii	Adapted from	N/A

c.iii.

[Maximum mark: 2]

21M.2.HL.TZ1.5c.iii

A device sends an impulse of electrical energy to maintain a regular heartbeat in a person. The device is powered by an alternating current (ac) supply connected to a step-up transformer that charges a capacitor of capacitance 30 μF.

The switch is moved to position B.

(c.iii)

The graph shows the variation with time of the charge in the capacitor as it is being discharged through the heart.

Determine the electrical resistance of the closed circuit with the switch in position B.

[2]

Markscheme

ALTERNATIVE 1

reads from the graph $τ = 1.6 ms$ ✓

so $R = \frac{0.0016}{30 \times 10^{- 6}} = 53 « Ω »$ ✓