First, substitute the values into the formula:
1/20 = 1/r1 + 1/75
Simplify the equation:
1/20 = (r1 + 75) / (r1 * 75)
Cross multiply to solve for r1:
75 = 20(r1 + 75)
75 = 20r1 + 1500
-1425 = 20r1
r1 = -71.25
Since resistance cannot be negative, we can conclude that the answer is not valid.
If R is the total resistance for a parallel circuit with two resistors of resistance r1 and r2, then 1/R = 1/r_(1) + 1/r_(2). Find the resistance, r1, if the total resistance R is 20 ohms, and r2 is 75 ohms. Round your answer to the nearest ohm if necessary.
A)16 ohms
B) 1,405 ohms
C) 27 ohms
D) 102 ohms
1 answer
3 answers