Advertisements
Advertisements
Question
How is the amount of heat produced calculated due to the passage of current in a metallic conductor? Derive an expression for it.
Solution
It is calculated by finding the amount of work done in sending the current through the conductor.
Let a current of i ampere flow in conductor having a potential difference of V volt across its ends for t second.
If Q be the amount of charge that flows in the conductor in t second.
Then Q = i × t coulomb
Since the amount of work done in: moving a charge Q across the ends of a conductor is W.
then W = Q × V joule
i.e., = i × t × V = Vit joule
or, the amount of heat produced Q = V it joule.
APPEARS IN
RELATED QUESTIONS
1 kWh = ________ J
State two factors on which the electrical energy consumed by an electrical appliance depends.
A simple electric circuit has a 30 V battery and a resistor ot 60 o. What will be the current in the circuit? The resistance of the oonnecting wires is negligible.
Which material is the calorimeter commonly made of? Give one reason for using this material.
What would happen and why, to an electric bulb when it is connected across a supply of voltage (i) lower (ii) higher than its proper rating?
A bulb is connected to a battery of e.m.f. 6V and internal resistance 2Ω A steady current of 0.5A flows through the bulb. Calculate the total energy supplied by the battery in 10 minutes.
A bulb is marked 100W, 220V and an electric heater is marked 2000 W, 220 V.
(i) What is the ratio between the resistances of these two devices?
(ii) How does the power-voltage rating of a device help us to decide about the type of leads (connecting wires) to be used for it?
(iii) In which of the above two devices, a thicker connecting wire of lead is required?
The average work done by a human heart while it beats once is 0.5 Joule. The power used by heart if it beats 72 times in a minute:
