Determine the power factor of 220V, 0.4A, 20W fluorescent lamp

Question

RRB Paper · Accepted Answer

To determine the power factor of a fluorescent lamp, we need to calculate the real power and the apparent power.

The real power (P) is given by:

P = V x I x cos(theta)

where V is the voltage, I is the current, and cos(theta) is the power factor.

The apparent power (S) is given by:

S = V x I

Using the values given in the problem, we can calculate:

P = 220 V x 0.4 A x cos(theta) = 88 cos(theta) W

S = 220 V x 0.4 A = 88 VA

We know that the lamp consumes 20 W of power, so the real power can be written as:

P = 20 W

Therefore, we can solve for the power factor:

cos(theta) = P / (V x I) = 20 W / (220 V x 0.4 A) = 0.2272

Therefore, the power factor of the fluorescent lamp is approximately 0.228.

0.228