There is a diagram for this question, but I can't post it, so I just describe it. There are four resistors R1,R2,R3,R4. When the switch S is opened, current only flows through R1,R3 and R4. R3 and R4 are parallel to each other, but in series with R1. Now the switch is closed, what happens to the voltage across each resistor? My solution is first to find out the current flows before and after the switch is closed through each resistor. I redrew the circuit into two circuits in series. First one is when switch is opened (R1,R34--I combined R3,R4 in parallel), the second one is when switch is closed (R1,R234--combined R2 with R34). Then I figured out that R234 < R34. Since V=IR. Now I am looking for the change in current before and after. My teacher told me current after the S is closed is bigger than the current when the S is opened? BUt is that because when you add more resistance to the circut, the current through the circuit will decrease? which in this case R234<R34, that's why I is more when the switch is closed? Thanks.