Question

4. The time lag between source and resistor voltages is most often reported as a phase difference, 0, between source and resistor. The phase difference is determined by equating the ratio of time lag and period to phase difference and 27: tlag = T 21 Since the period of the voltage cycle is 1/f, this relation simplifies to: 6 ft lag = 21 0 = 2.reft lag 2. The AC voltage source can be represented by the function, V = Vo cos (2aft + ), while the current in the circuit can be represented by the function, i = io cos (24ft). (The phase difference, o, represents the observed fact that the voltage across the resistor (which is directly in phase with the current) is not perfectly in phase with the source voltage.) Substitute these expressions into your equation and take the necessary derivative. 12. RL Circuits and Transformers S21.doc Page 4 of 18 = 3. Use the trigonometric identity, cos (a + b) = cos (a) cos (b) - sin (a) sin (b), to eliminate the "cos (2nft + )" term. 4. Examine your equation when 2aft = 0. Solve the resulting equation for cos 0. 5. Examine your equation when 2aft = 1/2. Solve the resulting equation for sin o. =

Answer 1

In an AC circuit, the time lag between the source and the resistor voltages is most often reported as a phase difference, 0, between the source and the resistor.

4) The phase difference is determined by equating the ratio of time lag and period to phase difference and 27:

tlag=T/21Since the period of the voltage cycle is 1/f, this relation simplifies to:6ftlag=210=2πftlag

The AC voltage source can be represented by the function, V = Vo cos (2πft +