- 11

- 0

**1. Homework Statement**

During the design of a new doppler radar unit, you have two circular plates with radius R = 3 cm and a plate separation of d = 5 mm. The magnitude of the electric field between the plates is given as:

E = (700 V/(m sec2))*(1-r/Rp)*t 2

where Rp is the radius of the plates, t is the time in sec and r is the distance from the axis of the plates (for r < Rp ).

a) What is amplitude of the induced magnetic field a distance 1.5 cm from the center axis joining the plates at time t = 2.9 sec?

**2. Homework Equations**

∫B.ds = [itex]\mu_{0}[/itex][itex]\epsilon_{0}[/itex] d[itex]\Phi[/itex]e/dt

**3. The Attempt at a Solution**

I did this problem as I worked out previous ones, taking the time derivative of the electric field to find the changing electric flux.

B=[itex]\mu_{0}[/itex][itex]\epsilon_{0}[/itex] pi*r^2/2*pi*r * dE/dt

B=[itex]\mu_{0}[/itex][itex]\epsilon_{0}[/itex] (.015/2) * 2*700t(1-.015/.03)

B = 1.69E-16

This answer is rejected by the software. I'm at a loss for what I'm missing here. I don't understand why I'm given the separation between the plates, I suspect that may be involved in the solution but I'm not seeing how. Thanks for any help.