Im not sure how to do this question in my Physics 2 class. Any help would be gre
ID: 1360631 • Letter: I
Question
Im not sure how to do this question in my Physics 2 class. Any help would be great!
A current balance is constructed in the following way: A 20-cm Iong section of wire is placed on top of the pan of an electronic balance used in a chemistry lab. Leads are clipped to it running into a power supply and through the supply to another segment of wire that is suspended directly above it, parallel with it. (See figure below.) The distance between the two wires is L = 2.0 cm. The power supply provides a current I running through the wires. When the power supply is switched on, the reading on the balance increases by 3.0 mg (1 mg = 10-6 kg). What is the current running through the wire?
Explanation / Answer
as current flows,wire exerts force on other wire.
according to, F / L = u0 i1 i2 / 2pid
and this force F will be equal to the weight of 3mg.
F = 3 x 10^-6 x 9.81 = 2.94 x 10^-5 N
2.94 x 10^-5 / 0.20 = (4pi x 10^-7 x I^2 ) / (2pi x 0.02)
I^2 = 14.7
I = 3.83 A