Question

Show how would you join three resistors,. Each of resistance 9 so that the equivalent resistance of the combination is
•13.5 and •6

Answer 1

(1) equivalent resistance =13.5

to get is this resistance 2 resistors must be connected in parallel and 1 resistor should be added

1/Rp=(1/9+19)ohm

1/Rp=2/9ohm

1/Rp=1/4.5 ohm

Rp=4.5 ohm

now adding 9 ohm

4.5 +9 ohm=13.5 ohm

(2)equivalent resistance =6 ohm

In any case of taking 3 resistors, 6 ohm is not possible

case1,take Rs=9+9+9=27which is not equal to 6

case2,take 1/Rp=1/9+1/9+1/9=3/9=1/3

Rp=3 which is not equal to 6

case3,take 2 resistors in series and one added to it in parallel

Rs=9+9=18 ;1/rp=1/9

add these both

18+1/9=(18(9)+1) /9= 162+1/9=163/9=18.12(approx) which is not equal to 6

case 4, it is already taken in 1