| ⇦ | 
| ⇨ |
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: - A straight conductor 0.1 m long moves in a uniform magnetic field 0.1 T.
- In insulators (CB is Conduction Band and VB is Valence Band)
- A boat which has a speed of 5 kmh⁻¹ in still water crosses river of width 1 km long
- Which one of the following statement is FALSE ?
- If the radioactive dacay constant of radium is 1.07 x 10⁻⁴ year⁻¹, then its half-life
Topics: Current Electricity
(136)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A straight conductor 0.1 m long moves in a uniform magnetic field 0.1 T.
- In insulators (CB is Conduction Band and VB is Valence Band)
- A boat which has a speed of 5 kmh⁻¹ in still water crosses river of width 1 km long
- Which one of the following statement is FALSE ?
- If the radioactive dacay constant of radium is 1.07 x 10⁻⁴ year⁻¹, then its half-life
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