A parallel-plate capacitor with circular plates of radius 35 mm is being discharged by a current of 3.5 A. At what radius (a) inside and (b) outside the capacitor gap is the magnitude of the induced magnetic field equal to 80% of its maximum value? (c) What is that maximum value?

Respuesta :

Explanation:

Given that,

Radius R= 35 mm

Current = 3.5 A

The magnetic field B is proportional to the r.

Magnetic field is maximum ,when r = R

(a). We need to calculate the radius inside the capacitor

[tex]\dfrac{0.80B_{max}}{B_{max}}=\dfrac{r_{1}}{R}[/tex]

[tex]r_{1}=0.80 R[/tex]

[tex]r_{1}=0.80\times35\times10^{-3}[/tex]

[tex]r_{1}=0.028\ m[/tex]

[tex]r_{1}=28\ mm[/tex]

The radius inside the capacitor is 28 mm.

(b). We need to calculate the radius outside the capacitor

[tex]\dfrac{0.80B_{max}}{B_{max}}=(\dfrac{r_2}{R})^{-1}[/tex]

[tex]r_{2}=\dfrac{35}{0.80}[/tex]

[tex]r_{2}=43.75\ mm[/tex]

The radius outside the capacitor is 43.75 mm.

(c). We need to calculate the maximum value

Using formula of magnetic field

[tex]B=\dfrac{\mu_{0}I}{2\pi R}[/tex]

Put the value into the formula

[tex]B=\dfrac{4\pi\times10^{-7}\times3.5}{2\times3.14\times35\times10^{-3}}[/tex]

[tex]B=2.00\times10^{-5}\ T[/tex]

The maximum value of magnetic field is [tex]2.00\times10^{-5}\ T[/tex].

Hence, This is the required solution.