Medium MCQ +4 / -1 PYQ · JEE Mains 2025

The equation of a wave travelling on a string is y = sin[20πx + 10πt], where x and t are distance and time in SI units. The minimum distance between two points having the same oscillating speed is :

  1. A <p>10 cm</p>
  2. B <p>2.5 cm</p>
  3. C <p>20 cm</p>
  4. D <p>5.0 cm</p> Correct answer

Solution

<p>The equation for a wave traveling on a string is given by $ y = \sin(20\pi x + 10\pi t) $, where $ x $ is the distance and $ t $ is the time in SI units. To find the minimum distance between two points having the same oscillating speed, we use the concept that this distance is half the wavelength $\left(\frac{\lambda}{2}\right)$.</p> <p>To find the wavelength $\lambda$:</p> <p>$ \lambda = \frac{2\pi}{k} $</p> <p>Here, the wave number $ k = 20\pi $. Thus,</p> <p>$ \lambda = \frac{2\pi}{20\pi} = \frac{1}{10} \text{ m} = 10 \text{ cm} $</p> <p>Thus, the minimum distance between two points having the same speed is:</p> <p>$ \text{Distance} = \frac{\lambda}{2} = \frac{10 \text{ cm}}{2} = 5 \text{ cm} $</p>

About this question

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

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