Question

Two resistors, each of 2Ω, are in parallel with one another. If a two more 2Ω resistors are added in parallel, how does the resistivity of the circuit change?

Resistance will double
Resistance will quadruple
Resistance will reduce by ½
Resistance will reduce by ¼

Answer 1

The resistance will reduce by 1/2

Total resistivity in parallel with all resistors having the same resistivity, the formula is

R total = R1/n with R1 being the value of 1 resistor and n the amount of resistors. Do in the first situation R tot is 1 ohm, while in second it is 0.5 ohm