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# Phy 5 Jan 05 Q2 watch

1. hi
Can anybody pls explain the last part of Q2 on Unit 5 Jan 05
how does the resultant electric field strength change 2 zero???

im guessing dis sort of Q wont *** up tormorrow jus it came u p last tyme...?
2. my answer was that ther must be another particle on the other side of Y. but that was a guess. lol
3. (Original post by cheerfulsakib)
hi
Can anybody pls explain the last part of Q2 on Unit 5 Jan 05
how does the resultant electric field strength change 2 zero???

im guessing dis sort of Q wont *** up tormorrow jus it came u p last tyme...?
4. wow....is there a Jan 05 paper? could someone email it to me? i would be erally grateful

are there papers from january in otheryears? does anybody have copies of them?

thanks
5. maybe wanna seperate the email address to prevent spam
6. (Original post by cheerfulsakib)
hi
Can anybody pls explain the last part of Q2 on Unit 5 Jan 05
how does the resultant electric field strength change 2 zero???

im guessing dis sort of Q wont *** up tormorrow jus it came u p last tyme...?
At Y: the force due to the -1uC point charge is attractive, the force due to the +3uC is repulsive. So the forces are in opposite directions. At Y, the +3uC charge is further away but is a bigger charge, whilst the -1uC charge is closer but smaller. So the magnitude of the two forces at Y are the same, but their directions are opposite. So the resultant field strength is zero.
7. Can ne one tell me how do this qu form the jan 05 paper

jan 05
qu 4

Explain,if the wire had twice the diameter, the current would have to be increased by a factor fo four to just lift the wire above the surface of the bench.

( the previous bit shows magnetic fields lines with a wire of lenght 0.4 m of mass 0.5g and the magnetic flux is 2 * 10 ^-2 T
Can ne one tell me how do this qu form the jan 05 paper

jan 05
qu 4

Explain,if the wire had twice the diameter, the current would have to be increased by a factor fo four to just lift the wire above the surface of the bench.

( the previous bit shows magnetic fields lines with a wire of lenght 0.4 m of mass 0.5g and the magnetic flux is 2 * 10 ^-2 T
If the diameter is 2 times more, the volume is 4 times more (since v=L(pi)r^2), so the mass is 4 times more, so the force needed to raise the wire is 4 times more, so the current needs to be 4 times more.
9. sweet thanks alot i knew it was something to do with somehting ^2. i was tryin to do it with the magnetic field strength and stuff and failin big time. thanks alot

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