Now replace the 8 Ω resistor with a 2 Ω resistor. The ideal supply stays at 12 V. Before calculating, predict whether the current increases or decreases. Then find the current and the voltage drop across each resistor.
Need a starting hint?
The resistors are still in series. Start by adding their resistances, then use I = V/R.
Show worked solution
Predict the change
Total resistance decreases while supply voltage stays fixed, so current increases.
Calculate the current
Total resistance is 4 + 2 = 6 Ω. Current is 12/6 = 2 A.
Calculate and check the voltage drops
Across 4 Ω: 2 × 4 = 8 V. Across 2 Ω: 2 × 2 = 4 V. These add up to 12 V.
Answer: Current increases to 2 A. The voltage drops are 8 V across 4 Ω and 4 V across 2 Ω.
Could you solve this without the earlier example? If not, revisit the first line where you got stuck.