SATHEE: Current Electricity - Result Question 81

Current Electricity - Result Question 81

86. Three equal resistors connected across a source of e.m.f. together dissipate 10 watt of power. What will be the power dissipated in watts if the same resistors are connected in parallel across the same source of e.m.f.?

[1998]

(a) 10

(b) $\frac{10}{3}$

(d) 90

Show Answer

Answer:

Correct Answer: 86. (d)

Solution:

(d) In series, Equivalent resistance $= 3 R$

Power $= \frac{V^{2}}{3 R} \Rightarrow 10 = \frac{V^{2}}{3 R} \Rightarrow V^{2} = 30 R$

In parallel, $\frac{1}{R^{'}} = \frac{1}{R} + \frac{1}{R} + \frac{1}{R} = \frac{3}{R}$

$∴$ Equivalent resistance $R^{'} = \frac{R}{3}$

$∴$ Power $= \frac{V^{2}}{R^{'}} = \frac{30 R}{R / 3} = 90 W$

If voltage $V$ remains same, then power consumed by a $n$ equal resistors in parallel is $n^{2}$ times that of power consumed in series.

Play Store

App Store

Ask SATHEE

Welcome to SATHEE !
Select from 'Menu' to explore our services, or ask SATHEE to get started. Let's embark on this journey of growth together! 🌐📚🚀🎓

I'm relatively new and can sometimes make mistakes.
If you notice any error, such as an incorrect solution, please use the thumbs down icon to aid my learning.
To begin your journey now, click on "I understand".

Current Electricity - Result Question 81

86. Three equal resistors connected across a source of e.m.f. together dissipate 10 watt of power. What will be the power dissipated in watts if the same resistors are connected in parallel across the same source of e.m.f.?

Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

Menu