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

Length of a string tied to two rigid supports is 40 cm. Maximum length (wavelength in cm) of a stationary wave produced on it is

  1. 20
  2. 40
  3. 80
  4. 120

Answer

When a string is plucked in middle, it vibrates with nodes at end and anti node in middle. Therefore 

λ/2 = length

λ = 2 × length = 2 × 40 = 80 cm

The correct option is C.