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Physics help? Resistance??

I've tried to answer these questions but I just can't get to right answer and I can't see what I'm doing wrong.

Could you run me through?

physics.JPG

With 11 I used the E=VIt eqn to come to 10800J, but the mark scheme says 9000J :colondollar:

12. I got the resistance to be 2 (1/(3/6)) and I= 3A (6/2) when the markscheme says I=0.67A

13. I just got stuck :colondollar:
11) Mark scheme is wrong. You are correct.
12) Total resistance in circuit is the 6 ohm on the left plus (in series with) the two 6 ohms in parallel on the right.
Try again to find the total resistance then use V=IR to find I
Reply 2
Original post by Stonebridge
11) Mark scheme is wrong. You are correct.
12) Total resistance in circuit is the 6 ohm on the left plus (in series with) the two 6 ohms in parallel on the right.
Try again to find the total resistance then use V=IR to find I


Ohhh good news for 11 then!

I also got 6/9 for the current in 12 (like in the markscheme) but now I'm having some trouble working out the V. I'm using V=IR but I'm not sure which resitance to use.
Original post by HiImSharon
Ohhh good news for 11 then!

I also got 6/9 for the current in 12 (like in the markscheme) but now I'm having some trouble working out the V. I'm using V=IR but I'm not sure which resitance to use.


Use the current you just found. That goes through the 6 ohm on the left. It's the pd across that they want.
Reply 4
Original post by Stonebridge
Use the current you just found. That goes through the 6 ohm on the left. It's the pd across that they want.


So I got 4V, which is also what the mark scheme says!

1 more question, I've worked out 13 now, but how would I go about doing this?
Resistance.JPG
Original post by HiImSharon
So I got 4V, which is also what the mark scheme says!

1 more question, I've worked out 13 now, but how would I go about doing this?
Resistance.JPG


Isn't it just V=IR? ( R = V/I )

Not sure why it's a problem if you can do the others.
Reply 6
Resistance...is futile (if <1ohm)
Original post by nicatre
Resistance...is futile (if <1ohm)


I'm sure this is a very profound statement, but I didn't have enough resistance to stop myself from saying this.
Reply 8
Original post by Stonebridge
I'm sure this is a very profound statement, but I didn't have enough resistance to stop myself from saying this.


The urge didn't over-power you with potential, you mean?
Reply 9
Original post by Stonebridge
Isn't it just V=IR? ( R = V/I )

Not sure why it's a problem if you can do the others.


Oooopsss I rearranged the equation wrong :colondollar:

Thanks for the help!

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