1. Kashif Bashirwww.kashifpaf.greatnow.com1 Alternating Voltage and Current Alternating Current Applications: The Sine Wave Alternating Current Voltage and Current values For a Sine Wave Frequency Period Wavelength Phase Angle Alternating Current Circuits with Resistance Three Phase AC Power

2. Kashif Bashirwww.kashifpaf.greatnow.com2 Alternating Current Applications

3. Kashif Bashirwww.kashifpaf.greatnow.com3 Values in A Sine Wave Algle  DegreesRadiansSin  Loop Voltage 000Zero 30  /6 0.50050% Max 45  /40.70770.7% 60  /30.86686.6% 90  /21.000+ve Max 180  0Zero 270 3  /2-1.000-ve Max 360 2  0Zero

4. Kashif Bashirwww.kashifpaf.greatnow.com4 Example: A sine wave of voltage varies from zero to a max. of 100 V. How much is the voltage at the instant of 30 degree of the cycle? 45?. Sol, V = V M sin  = 100 sin 30 V = 50 V V = 100sin 45= 70.7V

5. Kashif Bashirwww.kashifpaf.greatnow.com5 Alternating Current

6. Kashif Bashirwww.kashifpaf.greatnow.com6 Derivation of Average and RMS values for a Sine Wave Alternation

7. Kashif Bashirwww.kashifpaf.greatnow.com7 Root Mean-Square, Or Effective, Value rms value = 0.707 * peak value OrVrms = 0.707Vmaxand I max = 0.707I max Peak = 1/0.707 * rms = 1.414 * rms OrVmax = 1.414V rms and I max = 1.414I rms Peak to Peak value = 2.828 * rms value

8. Kashif Bashirwww.kashifpaf.greatnow.com8 Frequency Number of Cycles per second is the frequency in hertz units.

9. Kashif Bashirwww.kashifpaf.greatnow.com9 Period The amount of time it takes to go through one cycle is called the period. With the frequency of 50 Hz, as an example, the time for one cycle is 1/50 S. T = 1/f or f = 1/T

10. Kashif Bashirwww.kashifpaf.greatnow.com10 Wavelength When a periodic variation is considered with respect to distance, one cycle includes the wavelength, which is the length of one complete wave or cycle. OrThe distance traveled by the wave in one cycle is the wavelength. = velocity /frequency

11. Kashif Bashirwww.kashifpaf.greatnow.com11 Wavelength Cont.. Wavelength of radio waves: Fror electromagnetic radio waves, the velocity in air or vacuum is 186,000 mi/s, which is the speed of light. (cm) = (3 * 10 10 cm/s) / f(Hz) Wavelength of sound waves: = (1130 ft/s) / f Hz

12. Kashif Bashirwww.kashifpaf.greatnow.com12 Phase Angle Is the Angular difference in time b/w corresponding values in the cycles for two waveforms of the same frequency.