Question

erleliS 5s fe in tl estvation afact o suitch es are clases wken 1 2

Answer 1

When switch S1 is closed

C₁ and C₃ are in series

1/C₁₃ = 1/1 + 1/3

C₁₃ = 3/4 uF

C₂ and C₄ are in series

1/C₂₄ = 1/2 + 1/4

C₂₄ = 4/3 uF

and

above two combinations are in parallel

C_eq = C₁₃ + C₂₄

C_eq = 3/4 + 4/3 = 25/12 uF

so,

total charge

Q = C_eq * V

Q = 25 / 12 * 12

Q = 25 uC

Therefore,

Q (C₁ ) = 9 uC

Q ( C₂ ) = 16 uC

Q (C₃ ) = 9 uC

Q (C₄) = 16 uC

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Now When both switches are closed

C₁ and C₂ are in parallel

C₃ and C₄ are in parallel

so,

C₁₂ = 3 uF

C₃₄ = 7 uF

This is in series

so,

1/C_eq = 1/3 + 1/7

C_eq = 21/10 uF

so,

total charge

Q = 21 / 10 * 12

Q = 25.2 uC

Potential across C₁ and C₂ = Q/C = 25.2 / 3 = 8.4 V

Potential across C₃ and C₄ = 25.2 / 7 = 3.6 V

so,

Q (C₁ ) = 8.4 uC

Q ( C₂ ) = 16.8 uC

Q (C₃ ) = 10.8 uC

Q (C₄) = 14.4 uC

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In part (b), what is pent up ???? bad handwriting ....i am not able to read....However, I think you will be able to solve this with the above solution.

Please let me know if you have any doubt.