# Electric Fields Calculation Specimen Paper 2 AQAWatch

Thread starter 1 month ago
#1
An α particle makes a head-on collision with a gold nucleus containing 79 protons. The distance of closest approach of the α particle to the nucleus is 4.0 × 10^−14 m.
What electrostatic force acts on the gold nucleus when at this separation?

A) 9.1 × 10^−11 N
B) 23 N
C) 290 N
D) 1.4 × 10^20 N
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1 month ago
#2
Use the equation for the force between two point charges, what are the charges on the nucleus and alpha particle?
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Thread starter 1 month ago
#3
yeah i did that, keep getting B which isn't right
(Original post by justsomeguy17)
Use the equation for the force between two point charges, what are the charges on the nucleus and alpha particle?
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1 month ago
#4
post ur workings
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1 month ago
#5
23N is the correct answer, the mark scheme is wrong.
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Thread starter 1 month ago
#6
100% sure yeah?
my workings
F=(1/(4Pi*8.85x10^-12)) * (79x(1.6x10^-19)*2(1.6x10^-19)/(4x10^-14)^2)
=23N
(Original post by justsomeguy17)
23N is the correct answer, the mark scheme is wrong.
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1 month ago
#7
Yeah it's a specimen paper so they'll be a few mistakes. I've seen videos on youtube of people solving this question and they get the same answer 23N, I've also asked my physics teachers and they get 23N as well. Rest assured :P
(Original post by mahmed69)
100% sure yeah?
my workings
F=(1/(4Pi*8.85x10^-12)) * (79x(1.6x10^-19)*2(1.6x10^-19)/(4x10^-14)^2)
=23N
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Thread starter 1 month ago
#8
ah i seee i did the rest of the paper as well, some of the questions/answers are such nonsense. Just sums up AQA I guess

any predictions for tomorrow?
(Original post by justsomeguy17)
Yeah it's a specimen paper so they'll be a few mistakes. I've seen videos on youtube of people solving this question and they get the same answer 23N, I've also asked my physics teachers and they get 23N as well. Rest assured :P
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