In a uniform magnetic field with an induction of 0.1 T, a coil is placed from a conductor, the contour area

In a uniform magnetic field with an induction of 0.1 T, a coil is placed from a conductor, the contour area of which is 0.1 m ^ 2, and the resistance is 2 Ohms, so that its plane is perpendicular to the lines of induction. The coil is locked to a galvanometer. The total charge passed through the galvanometer when the coil is turned is 7.5 * 10 ^ -3 C. At what angle did the turn return

Given:
Induction B = 0.1 T;
Area S = 0.1 m ^ 2;
Resistance R = 2 ohms;
Charge q = 7.5 * 10 ^ (- 3) C;
Find the angle α;

Solution:
Φ = B * S * cos α;
q = I * ∆t;
I = Ei / R;
Ei = ∆Φ / ∆t;
Φ2 = B * S * cosα;
∆Φ = Φ2 – Φ1;
Φ1 = BS;
Hence,
q = Ei / R * Δt = ΔΦ / R = (B * S * cos α – B * S) / R;
cos α = ∣ (q * R + B * S) / (B * S) ∣ = 1 – (q * R) * / (B * S);
Substituting the known values, we get:
∣ cos α ∣ = 1 – (7.5 * 0.01 * 2) / (0.1 * 0.1) = 1 – 0.015 / 0.01 = 1 – 1.5 = – 1/2;
cos α = 1/2;
Angle α = 60 degrees.