Q3 · 2023 · Paper 2Complex unfamiliar8 marks
QUESTION 3 (8 marks)
Three charges are in a straight line as shown.
a)[2 marks]
Calculate the electric field strength at T. Show your working. Give your answer to two significant figures.
b)[6 marks]
Determine the value of . Show your working. Give your answer to two significant figures.
WORKED SOLUTION
8 marksQCAA guide · typeset solution
ANSWER
See worked solution below.
Worked solution
Sample response The response:
F recognises the sc
E=— acting on a point
q [1 mark]
28 « calculates the ele
=TT ‘1 mark!
5x10° t 1
=5.6x10° NC"
Electric field strength = 5.6x10°N C™ (to two
significant figures)
Sample response The response:
Using force e recognises the sc
Force between charges S and T: between charges
fp. - 1 24
ST 72
47é, r
5x10 x5x10°
=9x10°x Sa
r
_ 0.225
r identifies the rel.
. « identifies the rela
Force between charges T and U: and distance for
Fry = 1 a — charges S anc
Ame r? — charges T anc
9x 10° 5 x 107® x 40 x 107°
=9x x
(2r)?
_ 18
~ 4r2
0.45
oe
Equating the forces: « identifies the vec
Ip !-—IP —F oI Enenene TA marli
ie scenario relates to force
oint within an electric field
> electric field strength at T
e scenario relates to forces
‘ges [1 mark]
relationship between force
for
>and T [1 mark]
‘and U [1 mark]
vector relationship between
‘Ld
One QCAA sample method typeset for web; criterion wording is adapted from the official marking guide.
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