A circular loop of flexible iron wire has an initial circumference of 167 cm, bu

Question

A circular loop of flexible iron wire has an initial circumference of 167 cm, but its circumference is decreasing at a constant rate of 10.0 cm/seconds due to a tangential pull on the wire. The loop is in a constant uniform magnetic field of magnitude 0.900 T, which is oriented perpendicular to the plane of the loop. Assume that you are facing the loop and that the magnetic field points into the loop.

Find the magnitude of the emfinduced in the loop after exactly time 7.00 seconds has passed since the circumference of the loop started to decrease.

Explanation / Answer

The formula to apply here is = -/t

= BA

The area is changing.

The first area is found by r2. We are told the circumference is 167 cm, so 1.67 = 2r

Thus the initial radius is .266 m. The initial area is (.266)2 = .222 m2

After 7 seconds, the circumference will be 97 cm since it decreases at a rate of 10 cm/s. The radius at that point will be found by .97 = 2r. The final radius is .154 m. The final area is (.154)2 = .075 m2

A = .075 - .222 = -.147 m2

= -(.9)(-.147)/7

= .0189 V which can be stated as 18.9 mV

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.