DP Physics (last assessment 2024)

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Question 21M.2.HL.TZ1.d

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

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.

 

In practice, two electrodes connect the heart to the circuit. These electrodes introduce an additional capacitance.

Explain the effect of the electrode capacitance on the discharge time.

[2]

Markscheme

«the capacitors are in parallel hence» capacitances are added / more charge is stored
OR
Ceq is larger
OR
electrode capacitor charges and discharges ✓

«therefore» discharge takes longer/increases ✓

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