A flat coil of wire has an area A, N turns, and a resistance R. It is situated in a magnetic field, such that the normal to the coil is parallel to the magnetic field. The coil is then rotated through an angle of 90°, so that the normal becomes perpendicular to the magnetic field. The coil has an area of 1.5 10-3 m2, 50 turns, and a resistance of 166 Ω. During the time while it is rotating, a charge of 7.3 10-5 C flows in the coil. What is the magnitude of the magnetic field?

Explanation:

Expression for magnitude of the induced emf is as follows.

So, magnitude of the magnetic field is as follows.

                   B =

It is given that,

       A =

       Q =

       N = 50

       R = 166

Putting the given values into the above formula as follows.

              B =

                 =

                =

                =

                = 0.1615 T

Thus, we can conclude that magnitude of the magnetic field is 0.1615 T.

b.a device that inputs heat into a cool object