Part with an electric field and no magnetic field: electron  negative charge

e.)

8.) In the long solenoid [shown in cross section] in the figure to the right, the magnetic field varies according to the equation: B(t) = (2.00 t3 – 4.00 t2 + 0.800) T. The radius of the solenoid is R = 2.5 cm and r2 = 5 cm. Calculate the magnitude and direction of the force on an electron at P2 at time t = 2 s. When would the force on that electron be zero?

The circle is an E line chosen to circulate in the CCW sense. The path should be concentric with the solenoid. I missed just a little! The electric field circulates around . If is into the page, E circulates in the out of the page sense (CCW).

If r < R, then fills all the area enclosed by the E field line path.

If r > R, then fills the area out to R only

Solving for E and adding our CCW sense convention:

For r < R, the path is completely filled with time varying B field. For r > R, the path is only filled with time varying B field for the central circle of radius R. The magnetic field is non-zero only inside the solenoid.

The force on an electron will be or 8.01 x 10^-21 N

The force on an electron will be or 8.01 x 10^-21 N tangent in the CW sense.