Understanding 'Leading' and 'Lagging' voltage and current : EEE-1213

1.      A normal sine wave can be represented as,

2.      If the waveform is shifted to the right or left of 0°, the expression becomes

          where theta  is the angle in degrees or radians that the waveform has been shifted.

3.      If the waveform passes through the horizontal axis with a positive going (increasing with time) slope before 0°, as shown in Figure 2, the expression is:

4.      If the waveform passes through the horizontal axis with a positive-going slope after 0°, as shown in Figure 3, the expression is:

Examples:

Phase relationship between the sinusoidal waveform:

1.

Ans:

2.

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3.

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4.

Ans:

Both methods and answers are correct.

5.

Ans:

Note: