Question

A length of 20-gauge copper wire (of diameter 0.8118 mm) is formed into a circular loop with a radius of 30.0 cm. A magnetic field perpendicular to the plane of the loop increases from zero to 14.0 mT in 0.20 s. Find the average electrical power dissipated in the process.(The resistivity of copper is 1.72 × 10 − 8 1.72×10−8 Ω . m Ω.m)

Answer 1

Answer: 3 x 10^-24 watt

Explanation:

P ( resistivity) = 1.72e-8 (from the chart).

L= 2pi r

r= 30 cm.

R= pL/A

A= pi* r1^2

r1= 0.8118/2 * 10^-3 m

R= 1.68 x 10^-8 x (2x3.142x0.3)

= 3.24 x 10^-8

E=N do/dt

do= B* A

A= pi* 0.3^2

N=1

E = 1 x (14 x 3.142x 0.09) = 3.95

I=v/R

v=E,

I = 3.95 / 3.24 x 10^-8 = 1.22 x 10^8

P=I^2 x R.

= 3 x 10^-24 watt