Two resistors, each having a resistance of 17 O, are connected in parallel.

Question

Two resistors, each having a resistance of 17 Ω, are connected in parallel. What is the equivalent resistance of this combination?

Answer 1

Kennedy,

 

The applicable formula for the equivalent resistance, R, is

 

1/R = 1/R₁ + 1/R₂, 

 

where R₁ and R₂ are the resistances connected in parallel.

 

If R₁ = R₂ = 17 Ω, then

 

1/R = 1/17 + 1/17 = 2/17,

 

which means 

 

R = 17/2 = 8.5 Ω.

Answer 2

By the way, when connecting n EQUAL resistors of resistance R in parallel, a useful shorthand is:

 

R_eq = R/n

 

which is the corresponding formula to the case of connecting n equal resistors R in series:

 

R_eq = nR