2. Sample Papers
  3. NEET

NEET Sample Paper NEET Sample Test Paper-20

  • question_answer
    Equations of two progressive waves at a certain point in a medium are given by \[{{y}_{1}}=a\sin (\omega t+{{\phi }_{1}})\]and\[{{y}_{2}}=a\sin (\omega t+{{\phi }_{2}}).\]If amplitude and time period of resultant wave formed by the superposition of these two waves is same as that of both the waves, then \[{{\phi }_{1}}-{{\phi }_{2}}\]is

    A) \[\frac{\pi }{3}\]                                 

    B) \[\frac{2\pi }{3}\]                   

    C)      \[\frac{\pi }{6}\]                     

    D)      \[\frac{\pi }{4}\]    

    Correct Answer: B

    Solution :

    \[{{A}^{2}}=a_{1}^{2}+a_{2}^{2}+2{{a}_{1}}{{a}_{2}}\cos \phi \]                  (1) Here, \[\phi ={{\phi }_{1}}-{{\phi }_{2}},A={{a}_{1}}={{a}_{2}}=a\] Substituting these values in Eq. (1), we get\[\cos \phi =-\frac{1}{2}\] or \[\phi =\frac{2\pi }{3}\] Hence, the correction option is (b).


You need to login to perform this action.
You will be redirected in 3 sec spinner