Question

1. The drawing shows two long, straight wires thataresuspended from the ceiling.

The mass per unit linglh of each wire is 0.050 kg/m. Eachofthe four strings suspending

the wires has a length of 1.2 m. When the wires canyidenticalcurrents in opposite

directions, the angle between the strings holding the twowiresis 15° What is the current

in each wire?

2. A piece of copper wire has a resistance per unitlength 6.0x l0 ^-3 Ω /m. The wire is wound into athin, flat coil of manyturns that has a radius of 0.15 m. Theends of the wire areconnected to a 12 V battery. Find themagnetic field strength at thecenter of the coil.

3. A conducting coil of 1800 turns is connected toagalvanometer, and the total

resistance of the circuit is 50 Ω. The area of eachtum is 5.2x 10 ^-4 m². The coil is

moved from a region where the magnetic field is zero intoaregion where it is nonzero,

the normal to the coil being kept parallel to themagneticfield. The amount of charge

that is induced to move around the circuit is measured tobe9.0 x l0^-3 C. Find the

magnitude of the magnetic field.

[Such a device can be used to measure the magneticfieldstrength in a region of space and is called afluxmeter.]