| ⇦ | 
| ⇨ |
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: - One way in which the operation of a n-p-n transistor differs from that of a p-n-p
- Point masses m₁ and m₂ are placed at the opposite ends of a rigid rod of length L,
- When a light beam of frequency v is incident on a metal surface,
- A round disc of moment of inertia i₂ about its axis perpendicular to its plane
- A force of 10 newton acts on a body of mass 20 kg for 10 seconds. Change in its momentum
Topics: Current Electricity
(136)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- One way in which the operation of a n-p-n transistor differs from that of a p-n-p
- Point masses m₁ and m₂ are placed at the opposite ends of a rigid rod of length L,
- When a light beam of frequency v is incident on a metal surface,
- A round disc of moment of inertia i₂ about its axis perpendicular to its plane
- A force of 10 newton acts on a body of mass 20 kg for 10 seconds. Change in its momentum
Topics: Current Electricity (136)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
18000+ students are using NEETLab to improve their score. What about you?
Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.
Share this page with your friends
Leave a Reply