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1) What is the voltage across the capacitor immediately after switch S1 is close

ID: 1533846 • Letter: 1

Question

1) What is the voltage across the capacitor immediately after switch S1 is closed?

Vc = 0

Vc = V

Vc = 2V/3

2) What is the voltage across the capacitor after switch S1 has been closed for a very long time?

Vc = 0

Vc = V

Vc = 2V/3

3) After being closed a long time, switch 1 is opened and switch 2 is closed. What is the current through the right resistor immediately after switch 2 is closed?

IR = 0

IR = V/3R

IR = V/2R

IR = V/R

4) Now suppose both switches are closed. What is the voltage across the capacitor after a very long time?

Vc = 0

Vc = V

Vc = 2V/3

and explanation for each question please!

A circuit is wired up as shown below. The capacitor is initially uncharged and switches S1 and S2 are initially open. 2R S1 S2

Explanation / Answer

from the given circuit

1) What is the voltage across the capacitor immediately after switch S1 is closed?


the relation between Q,C,V is Q = C*V

   immediately after S1 is closed the charge on C is zero so the voltage is V = Q/C = 0 V


answer zero

2) What is the voltage across the capacitor after switch S1 has been closed for a very long time?


as the charges starts to deposit on the plates so that the current will be max in the bigening and after a long time the the capacitor fully charges so that no more charges will be deposited then


   then Q = c*V

       VC = Q/C

       VC = V which is maximum

answer V


3) After being closed a long time, switch 1 is opened and switch 2 is closed. What is the current through the right resistor immediately after switch 2 is closed?

in this case the s1 is open then circuit contains only capacitor of voltage V and resistance 2R are in series , then

   current will be from Ohm's law V = I*R ==> I = V/R = V/2R


answer is V/2R

4) Now suppose both switches are closed. What is the voltage across the capacitor after a very long time?


the capacitor and the resistor 2R are in parallel then the voltage across these will be same and current through R and C is same


   so V capacitor = V_2R
   = 2R/(1+2)R*V
= V(2/3 )

the answer is 2V/3