Question

Suppose a 60-turn coil lies in the plane of the page in a uniform magnetic field that is directed out of the page. The coil originally has an area of 0.325 m2. It is stretched to have no area in 0.100 s. What is the magnitude (in V) and direction (as seen from above) of the average induced emf if the uniform magnetic field has a strength of 1.60 T

Answer 1

emf = 312 V

Step-by-step explanation:

In this exercise the electromotive force is asked, for which we must use Faraday's law

emf =
`- N (d \Phi )/(dt)`- N dfi / dt

Ф = B. A = B A cos θ

bold type indicates vectors.

They indicate that the magnetic field is constant, the angle between the normal to the area and the magnetic field is parallel by local cosine values ​​1

It also indicates that the area is reduced from a₀ = 0.325 me² to a_f = 0 in a time interval of ΔT = 0.100 s, suppose that this reduction is linear

emf = -N B
`(dA)/(dT)`

emf = - N B (A_f - A₀) / Dt

we calculate

emf = - 60 1.60 (0 - 0.325) /0.100

emf = 312 V

The direction of this voltage is exiting the page