| ⇦ |  | ⇨ |
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:- If emf induced in a coil is 2 V by changing the current in it from 8 A to 6 A
- A vibrating string of certain length l under a tension T resonates with a mode
- Electrons of mass m with de-Broglie wavelength λ fall on the target in an X-ray tube.
- A point charge q is placed at a distance x/2 directly above the centre of a cube
- The ionisation potential of hydrogen-atom is -13.6 eV. An electron in the groundstate
Topics: Current Electricity
(136)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- If emf induced in a coil is 2 V by changing the current in it from 8 A to 6 A
- A vibrating string of certain length l under a tension T resonates with a mode
- Electrons of mass m with de-Broglie wavelength λ fall on the target in an X-ray tube.
- A point charge q is placed at a distance x/2 directly above the centre of a cube
- The ionisation potential of hydrogen-atom is -13.6 eV. An electron in the groundstate
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