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A Level Physics Practical Question Help

Hi, I need help with this question, I've drawn circuits of what I think the ohm-meter is measuring but I'm not too sure, as i get resistance of X is 150, but then I get two different values for the resistance of Y, 74.4 and 67.9

Also I don't have a mark scheme so I don't know what the correct answer is
(edited 5 years ago)
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You find X=150, looks fine to me.

Then to find y:
89.9(300+y) = 150(150+y)
26970 + 89.9y = 22500 + 150y
4470 = 60.1y
y = 74.4

Looks right to me.

Where are you getting 67.9 from?
Reply 2
Avatar for art_zab
art_zab
OP
5
Original post by Brain Damage
You find X=150, looks fine to me.

Then to find y:
89.9(300+y) = 150(150+y)
26970 + 89.9y = 22500 + 150y
4470 = 60.1y
y = 74.4

Looks right to me.

Where are you getting 67.9 from?


For the second circuit, the total resistance should be 55.4 ohms. If you substitute the resistance of Y to be 74.4 and resistance of X to be 150, then you will obtain , you will get that the total circuit resistance is 59.6 ohms, which is not what the question states it is. But, if the resistance of Y is 67.9 and resistance of X is 150, then the total circuit resistance would be 55.4, which is what the questions states it is. However, then this resistance of Y doesn't work for the other two circuits, so I can't find a consistent value of Y which works for all 3 circuits.
Sorry if I explained it in a long way
I see what you mean. Having the same problem, too. I don't know what the answer should be.
Reply 4
Avatar for art_zab
art_zab
OP
5
Original post by Brain Damage
I see what you mean. Having the same problem, too. I don't know what the answer should be

This is the mark scheme, both answers are correct...
Its just a really badly written question
AQA-PHA3B3X-W-MS-Jun17.pdf388.6KB
Original post by art_zab
This is the mark scheme, both answers are correct...
Its just a really badly written question

hahahaha, that's just brilliant

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