F=Bilsin@?? (1 Viewer)

[rosygirls92]

Hey thread! Anyone up to give me a hand on this question?

20 cm of wire is suspended horizontally on a spring balance. The wire is hanging in a horizontal mag field perpendicular to wire. Current flow is 25A and wire reading is 0.12N. When current is reversed reading is 0.08.
Ans is 4x10^-3

 

[Dumbledore]

err... what exactly are u trying to find?

 

[clintmyster]

you mentioned this which must mean a force 0.12N

the only variable i dont see is magnetic field, so have a shot at rearranging and work that out.

 

[harry4]

what did everyone think of cssa physics yesterday

i thought it was allright but started the 6 marker wrong and realised once i was nearly finished writing it

 

[anom1ly]

this question was in a mid-year assessment for me. but it was in multiple choice format.

you know, that without the force of the magnetic field on the conductor the conductor exerts a downward force of 10N on the spring balance. this is as its the average between 0.12 and 0.08. so you know that for force due to the magnetic field on the conductor is equal to 0.02N.

so put f=0.02 in the formula, and solve for B

 

[rosygirls92]

Wow such quick replies. Oh and I did forget to mension the question Bt tw heaps to anon But what if force was 9.8N?

 

[cybob101]

wait wat????, this is out of a text book you know

 

[anom1ly]

Wow such quick replies. Oh and I did forget to mension the question Bt tw heaps to anon But what if force was 9.8N?

well, 0.10N is a result of 9.8N x the objects mass, as f=mg.

but this isnt important for the question, you don't need to know the mass.