Two bulbs of 100w and 40w respectively connected in series across a 230v supply which bulb will glow bright and why? Last Answer : Since two bulbs are in series they will get equal amount of electrical current but as the supply voltage is constant across the bulb (P=V^2/R).So the resistance of 40W bulb is greater and voltage across 40W is more (V=IR) so 40W bulb will glow brighter....
What will happen if we give 220 Volt DC supply to a bulb or tube light? Last Answer : Bulbs (devices) for AC are designed to operate such that it offers high impedance to AC supply. Normally they have low resistance. When DC supply is applied, due to low resistance, the current through the lamp would be so high that it may damage the bulb element...
Why ELCB can't work if N input of ELCB do not connect to ground? Last Answer : ELCB is used to detect earth leakage fault. Once the phase and neutral are connected in an ELCB, the current will flow through phase and that much current will have to return neutral so resultant ... that full fault current will come back through ELCB, and there will be no difference in current....
What is power factor? Whether it should be high or low? Why? Last Answer : Power factor should be high in order to get smooth operation of the system. Low power factor means losses will be more.it is the ratio of true power to apparent power. It has to be ideally 1. If it ... ex: 0.95 to meet actual power load has to draw less current (V constant), result in less losses)...
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