Question

Find the amount of charge that will flow through the switch $S$ after it is closed,

• A. $300\text{ μC}$
• B. $400\text{ μC}$
• C. $500\text{ μC}$
• D. $100\text{ μC}$

Answer 1

Answer: (A)

When switch is open

$q=C_{e q} \, \times \, V \, $ (for both branches)
$q=2 \, \times \, 200=400$
Hence charge on each capacitor is $400 \, \mu C$ .
When switch's closed

$q_{6}=600 \, \mu C \, \Rightarrow \, q_{3}=300 \, \mu C$
Hence final arrangement

Final charge on both plates is $300$

Initial charge on both plates is zero
Hence charge flow is $300\,\mu C$ .