Medium MCQ +4 / -1 PYQ · JEE Mains 2020

For a transverse wave travelling along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m) of the are :

  1. A 1, 3, 5, .....
  2. B ${1 \over 1},{1 \over 3},{1 \over 5},$ ..... Correct answer
  3. C 1, 2, 3, .....
  4. D ${1 \over 2},{1 \over 4},{1 \over 6},$

Solution

$1.5 = \left( {2{n_1} + 1} \right){\lambda \over 2}$ ......(1) <br><br>5 = n<sub>2</sub>$\lambda$ .....(2) <br><br>(1) $\div$ (2) <br><br>${{1.5} \over 5} = {{\left( {2{n_1} + 1} \right)} \over {2{n_2}}}$ <br><br>$\Rightarrow$ 3n<sub>2</sub> = 10n<sub>1</sub> + 5 <br><br>n<sub>1</sub> = 1 ; n<sub>2</sub> = 5 $\Rightarrow$ $\lambda$ = 1 <br><br>n<sub>1</sub> = 4 ; n<sub>2</sub> = 15 $\Rightarrow$ $\lambda$ = 1/3 <br><br>n<sub>1</sub> = 7 ; n<sub>2</sub> = 25 $\Rightarrow$ $\lambda$ = 1/5

About this question

Subject: Physics · Chapter: Waves · Topic: Wave Motion and Types

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