Magnetic Field at a point between two capacitors

[Renaldo]

Homework Statement

A parallel plate capacitor has circular plates of radius 12.0 cm that are separated by a distance of 4.0 mm. The potential across the capacitor is increased at a constant rate of 1300 V/s. Determine the magnitude of the magnetic field between the plates at a distance r = 3.0 cm from the center.

Homework Equations

i_d = ε₀A(dE/dt)

B = [μ₀i_d/(2∏R²)]r

The Attempt at a Solution

i_d = ε₀A(dE/dt)

dE/dt = 1300 V/s
A = ∏R²
R = 0.12 m
ε₀ = 8.85E-12

i_d = 5.2E-10


B = [μ₀i_d/(2∏R²)]r

r = 0.03 m
R = 0.12 m
i_d = 5.2E-10
μ₀ = 1.26E-6

B = 2.17E-16

Correct answer is 3.39E-15

How do I get there?

 

[TSny]

dE/dt = 1300 V/s

Note that on the left you have the rate of change of E, but on the right you have the value of the rate of change of V.

[I get an answer that differs from the stated correct answer by a factor of 16.]

 

[Renaldo]

I thought E stood for V_emf. Does it stands for Electric field?

 

[TSny]

E is electric field.