The effective resistance between points L and M is

Options

A. `(2R)/(3)`
B. `(R )/(3)`
C. `(3r)/(5)`
D. `2r`

Answer

A

Explanation

Points M and Q are common.
Therefore, 2r in arm PQ and 1r in PM are in parallel between P and M.
`R _(rq) = (2 r xx 2r)/( 2r + 2r ) = r`
So, the modified circuit will be :

Effective resistance between L and M is given by,
`R _(eff) = (r xx (r +r ))/( r + (r +r )) = (2r)/(3)`