Question

Show how you would connect two 4 ohm resistors to produce a combined resistance of (a) 2 ohms (b) 8 ohms.

Answer 1

Connecting two 4 Ω resistors in parallel combination: 

`1/R=1/R_1+1/R_2` 

`1/R=1/4+1/4` 

`1/R=2/4 `

`1/R=1/2` 

R=2Ω  

Thus we get a 2Ω resistor. 

`R=R_1+R_2` 

R=4Ω+4Ω=8Ω 

Thus, we will get an 8 Ω resistor.
We should connect two 4 Ωresistors in parallel to get a resistance of 8 Ω