HEYA GUYS
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Please answer this
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a) State joules law of heating. Find an expression for amount of heat produced.
b) A torch bulb is rated 6V and 750mA. Calculate the energy consumed by the bulb in 4hours
Answers
Answer:
Ratings on the Torch Bulb: 6V and 750 mA.
Voltage across the bulb = V = 6 Volts
Current flowing through the bulb = I = 750 mA = 0.750 A
Power (rated) = Potential * current = V * I
P = 6 * 0.750 = 4.50 W
Time duration = t = 4 hours
Energy consumed = P * t = 4.50 * 4 = 18 W-hrs
or 0.018 kWh
Explanation:
We know that the heating impact of electric current when it travels in a circuit is because of collision among electrons of wire. Specifically, what is the amount of heat generated during flow of current through a wire and what are the parameters and conditions it is based upon. To answer all these questions, Joule gave a formula that describes this phenomenon precisely, and called as Joule’s Law.
Joule’s Law of Heating
The heat that is generated because of the current flow in an electric wire is described in Joules. The mathematical expression of Joule’s law is as explained below.
Joule’s first law
The joule’s first law shows the relationship between heat produced by a flowing electric current through a conductor.
Q = I2 R T
Where,
Q indicates amount of heat,
I shows electric current
R is the amount of electric resistance in conductor
T denotes time