A 113 ‑turn circular coil of radius 2.71 cm and negligible resistance is immersed in a uniform magnetic field that is perpendicular to the plane of the coil. The coil is connected to a 10.3 Ω resistor to create a closed circuit. During a time interval of 0.153 s, the magnetic field strength decreases uniformly from 0.441 T to zero. Find the energy, in millijoules, that is dissipated in the resistor during this time interval.

357 mJ

Explanation:

Parameters given:

Number of turns, N = 113

Radius, r = 2.71 cm = 0.0271 m

Resistance connected to coil, R = 10.3 ohms

Time interval, dt = 0.153 s

Change in magnetic field, dB = 0 - 0.441 T = - 0.441 T

First, we need to find the induced EMF in the coil. It is given as:

V = - (N * A * dB)/dt

A = area of coil = pi * r² = 3.142 * 0.0271² = 0.0023 m²

Therefore:

V = - (113 * 0.0023 * - 0.441) / 0.153

V = 0.75 V

Electrical energy dissipated in the resistor is given as:

E = V² / (R * t)

Where t is the time (0.153 secs)

E = (0.75²) / (10.3 * 0.153)

E = 0.357 J = 357 mJ

The energy dissipated in the resistor is 357 mJ

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.

96.77 amp

explanation:

rl = 250/100 = 2.5 ohms.

egl = 250 + (100 × 0.1) + 2 = 262 v.

at 700 r.p.m., eg2 = 262 × 700/1000 = 183.4 v.

if ia is the new current, then eg2 - 2 - (ia × 0.1) = 2.5 ia

which means this will give ia = 96.77 amp.