# 4.4 Problems

4.1 Determine an appropriate value of so that 20mA flows through the LED in figure P4.1 if . Assume the diode has a turn-on voltage and . Part (a) use the piecewise linear model; Part (b) use the simple piecewise linear model; part (C) use the ideal diode model.

4.2 Determine the current flowing in the following circuit if and if . Assume the diode has a turn-on voltage and . Part (a) use the piecewise linear model; (b) use the simple piecewise linear model; (c) use the ideal diode model

4.3 Determine an appropriate value of so that 20mA flows through the LED in the circuit of figure P4.2, above assuming the diode characterized by the following curve

4.4 In the following circuit, the input voltage is . Assume the diode is ideal and determine the average and RMS values of the input and output waveforms

4.5 Determine the current in the following circuit. Assume for the LED.

4.6 In the following circuit with Determine R so that the current in the circuit loop is 20 mA. Assume for the two light emitting diodes.

4.7 Determine the current flowing from the battery in the following circuit. Assume the diodes are ideal.

4.8 Determine the currents, , , and for the circuit shown if and . Assume the LEDs have and