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Question 19M.2.HL.TZ2.4di

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Date May 2019 Marks available [Maximum mark: 3] Reference code 19M.2.HL.TZ2.4di
Level HL Paper 2 Time zone TZ2
Command term Calculate Question number di Adapted from N/A
di.
[Maximum mark: 3]
19M.2.HL.TZ2.4di

When fully charged the space between the plates of the capacitor is filled with a dielectric with double the permittivity of a vacuum.

(di)

Calculate the change in the energy stored in the capacitor.

[3]

Markscheme

ALTERNATIVE 1

capacitance doubles and voltage halves ✔

since  E = 1 2 C V 2 energy halves   ✔

so change is «–»2.2×10–4 «J»  ✔

 

ALTERNATIVE 2

E = 1 2 C V 2  and  Q = C V  so  E = Q 2 2 C  ✔ 

capacitance doubles and charge unchanged so energy halves ✔

so change is «−»2.2 × 10−4 «J» ✔

Examiners report

By far the most common answer involved doubling the capacitance without considering the change in p.d. Almost all candidates who did this calculated a change in energy that scored 1 mark.

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