# how we use phasar to solve question

SAGAR SINGH - IIT DELHI
878 Points
13 years ago

Dear student,

A phasor diagram helps us to display the phase difference in a circuit that contains passive components.

From the origin (arbitrarily defined) we draw radial lines the length of which represents the magnitude of the variable. The angles between these lines represents the phase difference, i.e. if two lines have zero degrees between them then they are in phase, if they have 90 degrees between them they are out of phase by 90 degrees.

There is usually a reference phase angle that is represented by the conventional x-axis. Advancing phase is then conventionally shown in an anti-clockwise direction.

In text books a phasor quantity is usually represented as bold type i.e. V but when one writes a phasor quantity underlined i.e. V. A phasor that is at angle A to the reference angle is usually denoted as V<A where A may be +ve or -ve (leading or lagging respectively) to the reference.

The diagram below shows two phasors A and B. These are then combined to give a new phasor C.

In this case the magnitude of C will be given by (by Pythagoras' theorem):

and the phase difference between the reference angle (in this case phasor A) and C is given by:

All the best.

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