CAIE IGCSE Physics 4.3.2.6 Combined resistance of two resistors

Practise explaining how adding or removing a parallel resistor changes total resistance, current, and lamp brightness.

Exam points

state that a two-resistor parallel combination has less resistance than either resistor
predict current or lamp brightness changes when a parallel branch is added or removed

[Maximum number: 1]

Two resistors, with resistances $R_{1}$ and $R_{2}$ , are connected in parallel.
The resistance $R_{1}$ is greater than the resistance $R_{2}$ .

What is the resistance of the parallel combination?

less than either $R_{1}$ or $R_{2}$

equal to $R_{1}$

equal to $R_{2}$

the average of $R_{1}$ and $R_{2}$

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