Igcse Model Questions Vol1 2025 Physics Question 39

A rectangular coil of \(N = 50\) turns, each side \(0.12\ \text{m}\) by \(0.08\ \text{m}\), rotates at a constant angular speed of \(120\ \text{rev s}^{-1}\) in a uniform magnetic field of magnitude \(0.25\ \text{T}\). The coil has an internal resistance of \(2.0\ \Omega\) and is connected to an external resistor of \(8.0\ \Omega\). (a) Derive the expression for the maximum induced emf and calculate its value. (b) Determine the maximum current in the circuit. (c) Calculate the average power dissipated in the external resistor. (d) If the angular speed were halved while the number of turns were doubled, would the average power in the external resistor increase, decrease, or remain the same? Justify your answer.