a bulb is rated at 40W;220 V. Find the current. What is it resistance. if the given bulb is replaced by a bulb of rating of 25 W and 220 V, will there be any change in the value of current and resistance ? Justify your answer and determine the change.
Answers
Answer:
Step-by-step explanation:
Use the formula P = VI, assume V to be a constant value
When P is 100W, Current(I) is higher
but when P = 60W, current is lower (remember that V is constant)
then use V = IR, when current is high, resistance is low
Hence 60 W bulb has a higher resistance than 100W bulb
As simple as it can get, no need all the scientific calculations that the other “over exaggerating” answers stated
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Roger Davis
Roger Davis, Fixed TVs in my dad's store for 14 years.
Answered Mar 13, 2018 · Author has 129 answers and 68.3k answer views
Originally Answered: Which has more resistance: a 100 watt bulb or a 60 watts bulb?
Using Ohm’s Law:
E = I * R where E is potential in volts, I is current in amperes, and R is resistance in ohms.
P = I * E where P is Power in watts. 100 watts = I * 110 volts. 100 / 110 = 0.909 amps.
E = I * R. 110 volts= 0.909 amps * R ohms
110 / 0.909 = ~ 121 ohms for the 100 watt bulb.
P = I * E. 60 watts = I * 110 volts. 60 / 110 = 0.5454 amps.
E = I * R. 110 volts = .5454 amps * R ohms
110 / .5454 = 201.66 ohms for 60 watt bulb.
p= vi
i = p÷ v
=220 ÷ 40
= 5 .5 A
p = v×v÷r
=220×220÷40
=1210ohm