Question

39. The equivalent resistance between points A and
B IS:
(A)65/2 ohm (B) 45/2 ohm. (C) 5/2ohm. (D) 91/2 ohm​

Answer 1

Answer:

45/2 ohm

Explanation:

50 // 25 //50 ohm

Resultant=25/2

25/2 in series with 8 and 2 ohm

Resultant=25/2 + 8 + 2=45/2ohm

Answer 2

Answer:

The equivalent resistance between the points A and B is 22.5Ω.

Explanation:

In the given circuit, the resistors 15Ω & 10Ω, 10Ω & 40Ω and 30Ω & 20Ω are connected in series.

The equivalent resistance of the resistors connected in series is equal to the sum of individual resistances.

Thus, the equivalent resistance of each pair of series combination is

$R_1=15+10=25\Omega$

$R_2=10+40=50\Omega$

$R_3=30+20=50\Omega$

Now, the equivalent circuit is the parallel combination of these three resistances $R_1, R_2~ \&~R_3$.

The equivalent resistance of the resistors connected in parallel with each other is given by

$\dfrac{1}{R} = \dfrac{1}{R_1} + \dfrac{1}{R_2} +\dfrac{1}{R_3}$

$= \dfrac{1}{25} + \dfrac{1}{50} +\dfrac{1}{50}=0.08$

$\dfrac{1}{R}=0.08\implies R=\dfrac{1}{0.08}=12.5\Omega$

Now, the equivalent resistance R is in series with the other two resistances 2Ω and 8Ω.

Thus, the effective resistance in the circuit is

$R_{AB} = 2+12.5+8=22.5\Omega$

Therefore, the equivalent resistance between the points A and B is 22.5Ω.