question_answer

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

A)  20                                         

B)  80

C)  40                                         

D)  120

Correct Answer: B

Solution :

                When the string is plucked in the middle, it vibrates in one loop with nodes at fixed ends and. antinodes in the middle. So that,                \[\frac{{{\lambda }_{1}}}{2}=l\]                 \[{{\lambda }_{1}}=2\times 40=80\,cm\]