The given fig. shows two identical parallel plate capacitors connected to a battery with switch S is closed. The switch is now opened and free space between the plates of the capacitors is now filled with dielectric of K = 3. Then, ratio of energy stored in both capacitors before and after introduction of dielectric is ;

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

$\frac{5}{3}$

$\frac{3}{5}$

$\frac{7}{5}$

$\frac{5}{7}$

answer is B.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

As switch S is closed;
$V_{A} = V_{B} = V ∴ E_{i} = \frac{1}{2} {CV}^{2} + \frac{1}{2} {CV}^{2} = {CV}^{2}$
After introduction of slab as switch S is now opened, $V_{A} = V and C_{A} = 3 C & C_{B} = 3 C$ and Let ${V_{B}}^{'} =$ new pot. difference across capacitor B. Acc. to law of conservation of charge in case of capacitor B;
$CV = 3 {CV}_{B}^{'}$
$\Rightarrow V_{B}^{'} = \frac{V}{3}$
$∴ E_{f} = \frac{1}{2} C_{A} V^{2} + \frac{1}{2} C_{B} V_{B}^{2} = \frac{5}{3} {CV}^{2}$

Watch 3-min video & get full concept clarity

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET

How to Join IIT after 10th

🔥 Start Your JEE/NEET Prep at Just ₹1999 / month - Limited Offer! Check Now!

Get Expert Academic Guidance – Connect with a Counselor Today!

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET

How to Join IIT after 10th