The effective resistance between points P and Q of the electrical circuit shown in the figure is

Question

The effective resistance between points P and Q of the electrical circuit shown in the figure is (A) 2 operatornameRr /(R+r) (B) 8 R(R+r) /(3 R+r) (C) 2 r+4 R (D) 5 R /(2+2 r)

Tardigrade Admin · Accepted Answer

In a circuit, any circuit element placed between points at the same potential can be removed, without affecting the rest of the circuit. Here, by symmetry, points

A, B

and

C

are at same potential, for any potential difference between

P

and

Q

.
The circuit can therefore be reduced as shown below

Effective resistance,

R_{e q} = \frac{2 R r}{R + r}

.

Effective resistance, Re q=(2 R r/R+r).

Q. The effective resistance between points $P$ and $Q$ of the electrical circuit shown in the figure is

$2 Rr / (R + r)$

$8 R (R + r) / (3 R + r)$

$2 r + 4 R$

$5 R / (2 + 2 r)$

Q. The effective resistance between points P and Q of the electrical circuit shown in the figure is

2Rr/(R+r)

8R(R+r)/(3R+r)

2r+4R

5R/(2+2r)

Q. The effective resistance between points $P$ and $Q$ of the electrical circuit shown in the figure is

$2 Rr / (R + r)$

$8 R (R + r) / (3 R + r)$

$2 r + 4 R$

$5 R / (2 + 2 r)$