Electromagnetism Current Curcuits

Four resistors are connected to a battery as shown in the figure. The current in the battery is I, the battery emf is emf, and the resistor values are R1 = R, R2 = 2R, R3 = 4R, and R4 = 3R.

Picture:
http://www.webassign.net/serpop/p21-32.gif

(a) Rank the resistors according to the potential difference across them, from largest to smallest. (Use the form R1 for R1.)
R2<R1<R3<R4 (Correct)

(b) Determine the potential difference across each resistor in terms of emf. (Use E for emf, as necessary.)
ΔV1 = E/3 Answer is correct.
ΔV2 = 2E9 Answer is correct.
ΔV3 = 4E/9 Answer is correct.
ΔV4 = 2E/3 Answer is correct.

(c) Rank the resistors according to the current in them, from largest to smallest. Note any cases of equal currents.
I1 > I4 > I2 = I3 Answer is correct.

(d) Determine the current in each resistor in terms of I. (Use I, as necessary.)

(e) If R3 is increased, what happens to the current in each of the resistors?

I4 increases and I1, I2, and I3 decrease. Your answer is correct.

(f) In the limit that R3 → infinity, what are the new values of the current in each resistor in terms of I, the original current in the battery? (Use I, as necessary.)