A circuit contains two 90 Ω resistors connected in parallel. What's the total circuit resistance?

45ohms

Explanation:

Total resistance in parallel can be calculated by the addition of both resistors

1/R = 1/R1 + 1/R2

The value given are

R1 = 90 ohms, R2 = 90 ohms

1/R = 1/90+1/90

Take the LCM of both denominators

1/R = 2/90

1/R = 1/45

Cross multiply both sides

R*1 = 45*1

R = 45 ohms

Thus, the total reistance is 45 ohms

Total circuit resistance = 45ohms

Explanation:

Given that R1 = 90 and R2 = 90

Rt = total circuit resistance

Resistance in parallel:

Resistance in parallel is found by:

1/Rt = 1/R1 + 1/R2

1/Rt = 1/90 + 1/90

Take the L. C. M and simply

1/Rt = (1 + 1) / 90

1/Rt = 2 / 90

1/Rt = 1/45

Rt = 45 ohms

Total circuit resistance = 45ohms