Timer
00:00
Answers
A
B
C
D
E
Stats
Difficulty—
In an electric circuit, two resistors with resistance x and y are connected in parallel. In this case, if r is the combined resistance of these two resistors, then the reciprocal of r is equal to the sum of the reciprocals of x and y. What is r in terms of x and y?
A. xy
B. x + y
C. 1/(x + y)
D. xy/(x + y)
E. (x + y)/xy
The OA is D.
$$\frac{1}{r}=\frac{1}{x}+\frac{1}{y}=\frac{y+x}{xy}\ \Rightarrow r=\frac{xy}{x+y}$$
Option D.
A. xy
B. x + y
C. 1/(x + y)
D. xy/(x + y)
E. (x + y)/xy
The OA is D.
$$\frac{1}{r}=\frac{1}{x}+\frac{1}{y}=\frac{y+x}{xy}\ \Rightarrow r=\frac{xy}{x+y}$$
Option D.
