Embibe Experts Solutions for Chapter: Waves, Exercise 2: Level 2

For an electromagnetic wave, which of the following statements is true?

Three sinusoidal waves with the same angular frequency but with different amplitudes $A, \frac{A}{2}, \frac{A}{3}$ and phase angles $0, \frac{\pi }{2}$ and $\pi$ respectively move along the same direction and superpose with each other. The amplitude of the resultant wave is given by

A source of sound gives $5$ beats per second when sounded with another source of frequency $100 {\mathrm{s}}^{-1}.$ The second harmonic of the source together with a source of frequency $205 {\mathrm{s}}^{-1}$ gives $5$ beats per second. The frequency of the source is

Two sources $\mathrm{A}$ and $\mathrm{B}$ are sounding notes of frequency $680 \mathrm{Hz}.$A listener moves from $\mathrm{A}$ to $\mathrm{B}$ with a constant velocity u. If the speed of sound is $340 \mathrm{m}/\mathrm{s},$ what must be the value of $\mathrm{u}$ so that he hears 10 beats per sec ?

A source of sound emitting a note of frequency $200 \mathrm{Hz}$ moves towards an observer with a velocity $v$ equal to the velocity of sound. If the observer also moves away from the source with the same velocity $v,$ the apparent frequency heard by the observer is

A train whistling at constant frequency $n$ is moving towards a station at a constant speed $V$, then train goes past a stationary observer on the station. The frequency $n$ of the sound as heard by the observer is plotted as a function of time $t$. Identify the correct curve.

The apparent change in frequency of sound due to the relative motion between the observer and the source of sound is called

In a standing wave on a string rigidly fixed at both ends: