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Honors Physics II Problem Set 7b (due Wed Apr 13) Spring 2016 [In all assignments this semester, you are advised to first look at worked out examples as well as work out simple problems from your textbook before you attempt the homework problems assigned.] 1. (i) At a given instant the current and the induced emf in an inductor are as indicated in the figure. (a) Is the current increasing or decreasing? (b) The emf is 17 V, and the rate of change of the current is 25 kA/s; what is the value of the inductance? (ii) The inductance of a closely wound N-turn coil is such that an emf of 3.0 mV is induced when the current changes at the rate 5.0 A/s. A steady current of 8.0 A produces a magnetic flux of 40 µWb through each turn. (a) Calculate the inductance of the coil. (b) How many turns does the coil have? 2. The current i through a 4.6-H inductor varies with time t as shown. Calculate the induced emf during the time intervals (a) t = 0 to t = 2 ms, (b) t = 2 ms to t = 5 ms, and (c) t = 5 ms to t = 6 ms. (Ignore the discontinuities at the ends of the intervals.) 3. In the figure, E = 100 V, R1 = 10 Ω, R2 = 20 Ω, R3 = 30 Ω, and L = 2.0 H. Find the values of i1 and i2, (a) immediately after switch S is closed, (b) a long time later; (c) immediately after switch S is opened again; (d) a long time later. 4. A switch that connects a battery of emf E, a resistor of resistance R, and an inductor of inductance L, are connected in series. Suppose that the inductive time constant of the circuit is 37.5 ms. The current in the circuit is zero at time t = 0. At what time is the rate at which energy is dissipated in the resistor equal the rate at which energy is being stored in the inductor? 5. In an oscillating LC circuit, L = 1.13 mH and C = 3.88 µF. The maximum charge on the capacitor is 2.94 µC. Find the maximum current.