Length of a string tied to two rigid supports is 40 cm.Maximum length (wave length in cm) of a
stationary wave produced on it is
(a) 20 (b) 80 (c) 40 (d)120

When the string is plucked in the middle, it vibrates in one loop with nodes at fixed ends and an antinode in the middle.

Length of a string tied to two rigid supports is 40 cm

λ/2 = length

λ = 2 × length = 2 × 40 = 80 cm

Therefore,

Maximum length = 80 cm.