A 20V battery is connected to three branches in parallel. Branch 1 contains a single 10Ω resistor. Branch 2 contains a single 5Ω resistor. Branch 3 contains a 15Ω resistor in series with a switch S that can connect or disconnect an additional 15Ω resistor in parallel with it.
(a) With switch S open (additional resistor disconnected), calculate the current in each branch and the total current drawn from the battery.
(b) The switch is now closed so that the extra 15Ω resistor is connected in parallel with the original 15Ω resistor of Branch 3. Determine the new current in each branch and the new total current.
(c) Find the percentage change in the current through Branch 1 when the switch is closed.