# I NEED IMMEDIATE HELP for solving the magnitude and direction of current

Bk8907
ok here's the prob.

Two parallel wires are 20cm apart. EAch wire is 1.5 m long. The wire on the left carries 10 A of current up. Find the magnitude and direction of the current of the wire on the right ir it is REPELLED WITH A FORCE OF 10N.

.ultimate
Appy Felmmings left hand rule

Bk8907
LEFT hand? I thought there was only RIGHT hand

.ultimate
Strech Left hand's First finger, forefinger n thumb

First Finger - direction of magnetic field
Middle Finger - Direction of current
Thumb - direction of force on the conductor/wire

Right hand is for Electromagnetic Induction EMI

Magnitude can be calculated by F=B.I.L (or BqV in case or a moving charged partile)

Bk8907
what? wrong section?

NeoDevin
Questions like this belong in the homework help section.

Bk8907
ok, so from my problem, the current on the second wire is up (north) and what does B stand for again?

Bk8907
oh ok neo devin

.ultimate
Addendum - Apply Right hand thumb rule to find direction of magnetic field around the wire carrying current where thumb is for direction of current and curled fingers are for magnetic filed( this is different from motor and dyanmo rule)

Bk8907
so the current on the second wire IS north, but now with the 10N repulsion, how do i find magnitude?

.ultimate
B is magnitude of the magnetic filed

B= $$\frac {u_0.I}{2 \pi r}$$

$$u_0$$ permeability of vacuum

(Dont have enough knowledge to assist in this context, sorry)

Bk8907
wow what a formula! i use F=2K'I/r