1. Anatomy of wave

2. On the Oscilloscope
Wavelength is 5.75 div. So the period is (5.75 div)*(5ms/div)=28.75 ms
P-P voltage is :
(6div)*(2 v/div)=12V
5 ms
2 V

3. Phase delay between two waves
Wave A is ahead of Wave B.
If we choose 0 degree for start of wave A, Wave B starts at 45 degrees.
Wave A is /8 (45/360=1/8) ahead of B.
You can also look at the peak positions.
Wave A peaks at 90 degrees and Wave B peaks at 135 degrees. The phase delay is =45 degrees.

5. Measuring delay using Oscilloscope
One division
“White” wave is ahead of “blue” wave by 0.8 division (look at the peaks)
The periods (wavelength) of both waves are 5 divisions.
The delay is (0.8/5)*360=58 degrees (or 1 radian).

6. Another example: Wave 1 is about 1.9 divisions ahead of wave 2.
Each wave has period of 15 divisions.
Delay is (1.9/15)*360=45 degrees.

7. Another example: Wave 1 is about 3.75 divisions ahead of wave 2.
Each wave has period of 15 divisions.
Delay is (3.75/15)*360=90 degrees.

8. Another example: Wave 1 is about 7.5 divisions ahead of wave 2.
Each wave has period of 15 divisions.
Delay is (7.5/15)*360=180 degrees.

9. The current and voltages on a device may not be in phase.
R, L and C in AC circuits:
The current and voltages on a device may not be in phase.

10. In resistors
Current and voltage are in phase.

11. Current is ahead of voltage
In capacitors:
Current is ahead of voltage

12. Voltage is ahead of current
In Inductors:
Voltage is ahead of current
Y. Ataiiyan, PHYS42, Fall 2011