Question

How does the total energy stored in the capacitors in the circuit shown in the figure change when first switch $K_1$ is closed (process-1) and then switch $K_2$ is also closed (process-2). Assume that all capacitor were initially uncharged?

• A. Increases in process-1
• B. Increases in process-2
• C. Decreases in process-2
• D. Magnitude of Energy in process-2 is less than that in process-1

Answer 1

Answer: (A), (B), (D)

The correct options are
A Increases in process-1
B Increases in process-2
D Magnitude of Energy in process-2 is less than that in process-1

As all capacitor were initially uncharged so no energy stored in the capacitors.
When $K_1$ is closed, only one capacitor on the right will charge. So energy stored in capacitor is $E_1=\frac{1}{2}C{U}^2$. Thus energy increases in process -1.
For process 2, the effective capacitance will be 5C/3. So energy stored in capacitor is $E_1=\frac{1}{2}5/3C{U}^2$. Thus energy increases in process -2.
But increase in energy in process 2 is less than increase in energy in process 1.