Hopefully my year 11 skills aren't too rusty lol. If there are any mistakes, feel free to correct me.
a) For resistance in series, simply add them together.
For resistance in separate lines in parallel circuits, 1/R(total) = 1/R1 + 1/R2 (i.e. the resistance in each line)
b) Voltage remains constant for both of the lines, so calculating the current in the top one by Ohm's law, V = IR
I = 12/10 = 1.2
Second line, I = 12/2 = 6
Adding together to find total current, 7.2A
c) Voltage is spread evenly across both lines, so voltage drop across top left resistor = IR = 1.2 x 4 = 4.8V
Voltage drop across top right one = 1.2 x 6 = 7.2V
Voltage drop across the middle resistor = 2 x 6 = 12V
e) i. Potential difference between X and Y is zero as voltage is even spread across parallel circuits.
ii. V = IR = 6 x 2 = 12V
iii. Top left resistor uses 4.8V (previously calculated) therefore potential difference between X and W is 4.8V
iv. At point Y, there has been no loss of energy through a resistor.
At V, 12V has been used so potential difference of 12V.
v. At point W, 4.8V has been used so there remains 7.2V at point W.
At point Z, 12V has been used so the potential difference between W and Z is 7.2V.
f) Power = VI = 12 x (current which you calculate earlier)
g) Already known the current passing through each resistor so use P = VI for each
