Solutions: Chapter 21, Problems 4, 7

Chapter 21, Problem 4. A single loop of wire with an area of x₁ m² is in a uniform magnetic field that has an initial value of x₂ T, is perpendicular to the plane of the loop, and is decreased with the constant rate of x₃ T/s.
(a) What emf is induced in this loop?

(b) If the loop has a resistance of x₄ Ω, find the current induced in the loop.

Chapter 21, problem 7. A closely wound rectangular coil of N turns has dimensions of x₁ cm by x₂ cm. The plane of the coil is rotated from a position where it makes an angle of x₃ᵒ with a magnetic field of x₄ T to a position perpendicular to the field. The rotation takes x₅ s.
What is average emf induced on the coil?

---