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# A 4 µF Capacitor is Charged by a 200 V Supply. It is Then Disconnected from the Supply, and is Connected to Another Uncharged 2 µF Capacitor. How Much Electrostatic Energy of the First Capacitor is Lost in the Form of Heat and Electromagnetic Radiation? - CBSE (Science) Class 12 - Physics

#### Question

A 4 µF capacitor is charged by a 200 V supply. It is then disconnected from the supply, and is connected to another uncharged 2 µF capacitor. How much electrostatic energy of the first capacitor is lost in the form of heat and electromagnetic radiation?

#### Solution

Capacitance of a charged capacitor, C_1=muF=4xx10^-6 F

Supply voltage, V1 = 200 V

Electrostatic energy stored in Cis given by,

E_1=1/2C_1V_1^2

=1/2xx4xx10^-6xx(200)^2

=8xx10^-2 J

Capacitance of an uncharged capacitor, C_2=2muF=2xx10^-6F

When C2 is connected to the circuit, the potential acquired by it is V2.

According to the conservation of charge, initial charge on capacitor C1 is equal to the final charge on capacitors, C1 and C2.

V_2(C_1+C_2)=C_1V_1

V_2xx(4+2)xx10^-6=4xx10^-6xx200

V_2=400/3V

Electrostatic energy for the combination of two capacitors is given by,

E_2=1/2(C_1+C_2)V_2^2

=1/2(2+4)xx10^-6xx(400/3)^2

=5.33 xx10^-2 J

Hence, amount of electrostatic energy lost by capacitor C1

E1 − E2

= 0.08 − 0.0533 = 0.0267

= 2.67 × 10−2 J

Is there an error in this question or solution?

#### APPEARS IN

NCERT Solution for Physics Textbook for Class 12 (2018 to Current)
Chapter 2: Electrostatic Potential and Capacitance
Q: 27 | Page no. 90
Solution A 4 µF Capacitor is Charged by a 200 V Supply. It is Then Disconnected from the Supply, and is Connected to Another Uncharged 2 µF Capacitor. How Much Electrostatic Energy of the First Capacitor is Lost in the Form of Heat and Electromagnetic Radiation? Concept: Electrostatics of Conductors.
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