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The identical cells connected in series are needed to heat a wire of length one meter and radius ‘r’ by 10⁰C in time ‘t’. How many cells will be required to heat the wire of length two meter of the same radius by the same temperature in time ‘t’?
Options
(a) 10
(b) 20
(c) 30
(d) 40
Correct Answer:
20
Explanation:
Resistance is directly proportional to length of the wire. As length is doubled so mass is doubled and resistance is doubled. We have
(10 E)² / R . t = mS∆T,
Now, (nE)²t / 2R = (2m) S∆T
⇒ n²E²t / 2R = 2 . 10²E²t / R
⇒ n = 20
Related Questions: - What is the energy released by fission of 1 g of U²³⁵?
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Topics: Current Electricity
(136)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- What is the energy released by fission of 1 g of U²³⁵?
- A charge Q is enclosed by a Gaussian spherical surface of radius R
- A tuned amplifier circuit is used to generate a carrier frequency of 2 MHz
- A heavy small sized sphere is suspended by a string of length l.The sphere rotates
- An insulated container of gas has two champers seperated by an insulating partition.
Topics: Current Electricity (136)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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