A magnetic field between the poles of the electromagnet is uniform at any time, but its magnitude is increasing at the rate of 0.020T/s. The area of the conducting loop in the field is 120 cm2 , and the total circuit resistance, including the meter is 5.0 ohms. (a)Find the induced emf and the induced current in the circuit.(b) If the loop is replaced by one made of an insulator, what effect does this have on the induced emf and induced current?

a) -2.4*10^-4 V

   4.8*10^-5 A

b)  emf = 0

   induced current = 0

Explanation:

a) The induced emf is given by the following formula:

   ( 1 )

A: area of the loop = 120 cm^2 = 120 (10^-2)^2 = 0.012m^2

The area is constant and dB/dt = 0.020T/s

By replacing in  the values of the parameters in the equation (1) you obtain:

The induced current is:

b) If the loop is made of an insulator, electrons in the wire does not feel the change in the magnetic flux. Due to that, there is no a work over the electrons, and consequantly, there is neither emf nor induced current.

this could be newton#'s law of cooling. the cooling curve is exponential

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.