Saved Bookmarks
| 1. |
A 20 watt, 50 V lamp is connected in series to a.c. mains of 250 V, 50 Hz. Calculate to value of capacitor to run the lamp. |
|
Answer» Here, ` p = 20` watt, `V = 50` volt `E_(v) = 250 V, C = ?, v = 50 Hz` `I = (P)/(V) = (20)/(50) = 0.4 A` `R = (V)/(I) = (50)/(0.4) = 125 ohm` `Z = (E_(v))/(I_(v)) = (E_(v))/(I) = (250)/(0.4) = 625 ohm` `X_(C ) = sqrt(Z^(2) - R^(2)) = sqrt(625^(2) - 125^(2)) = 250 sqrt 6` As `X_(C ) = (1)/(omega C) = (1)/(2 pi v C) = 250 sqrt 6` `:. C = (1)/(2 pi v xx 250 sqrt 6)` `= (1)/(2 xx 3.14 xx 50 xx 250 sqrt 6)` farad `C = 0.052 xx 10^(-4) F 5.2 mu F` |
|