Here's a basic sec 2 physics question. But I tried out 2 ways
and yielded TWO different answers. One of the methods is wrong I
suppose. Please tell me which one is the incorrect method.
2 identeical resistors each of resistance R are placed in
parallel. The effective resistance is
A 2R
B 1
C R^2
D R/2
First method: 1/R + 1/R = 2/R
So 1/R = 2/R
R = 1 /
2/R
= R/2
Second method: 1/R + 1/R =
2/R
1/R = 2/R
Using cross multiplication
you'd get R = 2R!!!
Isn't this weird?
PS: The red refers to the answers and division line. (:
both also wrong
how can 1/R = 2/R
u must label them clearly.
1/Rtot = 2/R
2Rtot=
R (X
multiplication)
Rtot= R/2