AQA GCSE Physics (9-1): Resistance in Series and Parallel. Electricity Revision Series.

1)a) It is a series circuit, so just add the resistances together.
2+4+4= 10ohms.
b) To find the current (the ammeter reading), use V=IR. Rearrange for I to get I= V/R
20V/10ohms = 2A

2)For all of these questions, the potential difference is the same (parallel circuit). V=6V.
a) rearranging V=IR for I, you get I=V/R.
6V/2ohms = 3A.
b) 6V/3ohms = 2A
c) resistors are in series so add their values for total resistance (2+4=6ohms), then 6V/6ohms = 1A.
d) remember, the total current here is equal to the sum of the current down each branch, so..
3A + 2A + 1A = 6A.