Question

3. When two resistors are connected in series
their effective resistance is 30. When the
are connected in parallel, their effective
resistance is 20. What are the values of
the two resistances?​

Answer 1

Answer:

Hi there!!!

Explanation:

The (a) represents resistors in series and (b) represents resistors in parallel.

The formula for resistors in series is: req = r1 + r2

The formula for resistors in parallel is : 1/ req = 1/ r1 +1/ r2

Applying the values,

r1 + r2 = 30 ...................... (1)

r2 * r1 / r1+ r2 = 20..........(2)

20 = r1 *r2 / 30.................(3)

from  (1), r2 = 30 - r1

sub. in (3),

we get : r1² -30r1 +600 = 0

On solving this eqn, you will get r1 and sub. the value in any one eqn, you will get r2.

Hope my answer helps u......