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प्रश्न
What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
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उत्तर
Joule's law of heating states that heat produced in the resistor is
- directly proportional to the square of the current.
- directly proportional to the resistance.
- directly proportional to the current.
Mathematically,
H = i2Rt
where,
H = Heat produced
I = Current
R = Resistance
t = time
Experimental demonstration
- Take a water heating immersion rod, water, bucket, thermometer, regulator.
- Immerse the water heating immersion rod in the water and measure the time taken to heat the water upto a certain temperature.
- Now increase the current to double with the help of regulator and now measure the time taken to heat the water upto the same temperature.
Then, we will observe that time taken in second case will be one fourth the time taken in earlier case. Hence, it verifies the Joule's law of heating.
Electric fuse, toaster, oven, kettle, are the four applications of Joule's law of heating in daily life.
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संबंधित प्रश्न
Why does the cord of an electric heater not glow while the heating element does?
An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
Why is a series arrangement not used for connecting domestic electrical appliances in a circuit?
Why does the connecting cord of an electric heater not glow hot while the heating element does?
Explain why, tungsten is used for making the filaments of electric bulbs.
A heating coil has a resistance of 200 Ω. At what rate will heat be produced in it when a current of 2.5 A flows through it?
The elements of electrical heating devices are usually made of:
(a) tungsten
(b) bronze
(c) nichrome
(d) argon
How does the wire in the filament of a light bulb behave differently to the other wires in the circuit when the current flows?
What property of the filament wire accounts for this difference?
Two exactly similar heating resistances are connected (i) in series, and (ii) in parallel, in two different circuits, one by one. If the same current is passed through both the combinations, is more heat obtained per minute when they are connected in series or when they are connected in parallel? Give reason for your answer.
Give Scientific reason
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster etc, an alloy such as Nichrome is used, not pure metals.
Solve the following example.
Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
Answer the following question:
what is the heating effect of the electric current? state any four applications of it?
Mark the correct choice
- Assertion: Electric appliances with a metallic body have three wire connections.
- Reason: Three-pin connections reduce the heating of the connecting wires.
An electric component used as a safety device is electric circuit is ______.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness. Both of them connected the wires as shown in the circuit given in the following figure. The current flowing in both the circuits is the same.
- Will the heat produced in both cases be equal? Explain.
- Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain.
Fuse is a strip of alloy wire which is made up of lead and tin with a very low ______.
Assertion: A current-carrying wire should be charged.
Reason: The current in a wire is due to the flow of free electrons in a definite direction.
