Question Five a) State Gauss' law. (1 mark) b) Explain why extrinsic semiconductors behave essentially as intrinsic semiconductors at high temperatures. (2 marks) c) In an L-R-C series circuit, R=30092, L=0.4000H and C = 6.0 x 10F. When the ac source operates at the resonance frequency of the circuit, the current amplitude is 0.500 A. (i) What is the voltage amplitude of the source? (4 marks) (ii) What is the amplitude of the voltage across the resistor, across the inductor, and across the capacitor? (iii) What is the average power supplied by the source? (4 marks) (4 marks) d) The 19th-century inventor Nikola Tesla proposed to transmit electric power via sinusoidal electromagnetic waves. Suppose power is to be transmitted in a beam of cross-sectional area 100m. What electric- and magnetic-field amplitudes are required to transmit an amount of power comparable to that handled by modern transmission lines (that carry voltages and currents of the order of 500 kV and 1000 A)? (5 marks)