The diameter of a toroid is 22 cm. It has a cross-sectional area of 0.500 cm². Determine the number of turns required to make the inductance of the toroid 0.200 mH.  

You are provided with a graph of the potential difference against time below for a 15 mH inductor. If the current at t = 0 ms is 0.80 A, calculate the current when t = 8 ms. The plotted potential difference is defined by $V_L=-LdI/dt$

An inductive coil experiences a current given by I = I₀e ^{- (tR / L)}. Calculate the potential difference across the coil for L = 16 mH, I₀ = 30 mA, and R = 20 Ω at i) t = 0 ms and ii) t = 4.0 ms.