Question

1. Is the magnetic pole of the Earth nearest the geographic North Pole a magnetic north or a magnetic south pole?

2. A current in a solenoid coil creates a magnetic field inside that coil. The field strength is directly proportional to:

a. the coil area

b. the current.

c. Both A and B are valid choices.

d. None of the above choices are valid.

3. A double loop of wire (making 2 turns) is in the xy-plane centered at the origin. A uniform magnetic field is increasing at a constant rate in the +z-direction. Viewed from the +z-axis, in which direction is the induced magnetic field in the loop?

4. A loop of area 0.250 m2 is in a uniform 0.0200-T magnetic field. Is this a physically-possible situation? If so, what angle does the normal to the plane of the loop make with the direction of the magnetic field if the flux through the loop is 3.21 × 10?3 T m2 ?

Answer 1

1. the north pole of a magnet poiints towards geographic north pole ( and is attracetd to magnetic south pole)

hence

the geographic north pole of the earth is closest to the magnetic south pole of the earths magnet

2. magnetic field inside a coil is given by B - mu*N*i/L

where i is current, L is length of the solenoid, N is numder of turns

hence

it is proportinoal to current

hence

option a) current

3. given n = 2 ( two loops)

dB/dt = k ( constnat) along +z axis

hence, induced magnetic field in the loop is along -z axis ( from lenz's law)

4. A = 0.25 m^2

B = 0.02 T

this is possible

now maximum flus through the coil = phi = BA = 0.005 T m^2

hence

BAcos(tehta) = 3.21*10^-3

hence

theta = 50.058883358 deg

hence normal to the coil makes angle theta with the magnetic field