A(n) 34 cm length of wire when used as a resistor has a resistance of 0.00372 Ω. The ends of the wire are connected to form a circular loop, and the plane of the loop is positioned at right angles to a uniform magnetic field that is increasing at the rate of 0.0633 T/s. At what rate is thermal energy generated in the wire? Answer in units of µW.

Respuesta :

Answer:

[tex]91.1\ \mu W[/tex]

Explanation:

P = Perimeter of loop = 34 cm

r = Radius

[tex]\frac{dB}{dt}[/tex] = Rate of change of magnetic field = 0.0633 T/s

A = Area = [tex]\pi r^2[/tex]

R = Resistance = 0.00372 Ω

Perimeter is given by

[tex]P=2\pi r\\\Rightarrow r=\frac{P}{2\pi}\\\Rightarrow r=\frac{0.34}{2\pi}\\\Rightarrow r=0.05411\ m[/tex]

Induced emf is given by

[tex]\epsilon=A\frac{dB}{dt}\\\Rightarrow \epsilon=\pi r^2\frac{dB}{dt}[/tex]

Induced current is given by

[tex]I=\frac{\epsilon}{R}\\\Rightarrow I=\left(\frac{1}{R}\pi r^2\frac{dB}{dt}\right)[/tex]

Power is given by

[tex]P=I^2R\\\Rightarrow P=\left(\frac{1}{R}\pi r^2\frac{dB}{dt}\right)^2 R\\\Rightarrow P=\frac{1}{R}\left(\pi r^2\frac{dB}{dt}\right)^2\\\Rightarrow P=\frac{1}{0.00372}\left(\pi 0.05411^2\times 0.0633\right)^2\\\Rightarrow P=9.11\times 10^{-5}\ W=91.1\ \mu W[/tex]

The thermal energy generation rate is [tex]91.1\ \mu W[/tex]