Resistors in Series & Parallel Flashcards

All 4 cards in this deck

What is the total (net) resistance of resistors connected in series?

e.g. a $10\ \Omega$ and a $20\ \Omega$ resistor in series

$R_{total} = R_1 + R_2 + ...$

$= 10 + 20 = 30\ \Omega$

Why is the net resistance of two resistors in parallel less than the resistance of either resistor on its own?

There are more paths for the current, so for the same p.d. the total current is larger, which means a lower total resistance.

How does the overall resistance of a circuit change as more identical resistors are added in parallel?

It decreases, and the relationship is non-linear (it decreases at a decreasing rate).

Why does adding another resistor in series increase the total resistance of a circuit?

The resistors must share the supply p.d., so each has less p.d. across it and the current through the whole circuit falls; less current for the same supply p.d. means more total resistance.