Question:
An observer is standing below a freely falling source of sound of frequency 900 Hz. The change in the frequency noticed by the observer after 3 seconds of free fall of the source is (speed of sound in air is 330 ms\(^{-1}\) and acceleration due to gravity = 10 ms\(^{-2}\))
An observer is standing below a freely falling source of sound of frequency 900 Hz. The change in the frequency noticed by the observer after 3 seconds of free fall of the source is (speed of sound in air is 330 ms\(^{-1}\) and acceleration due to gravity = 10 ms\(^{-2}\))
Show Hint
The time interval between maxima and minima in a beat pattern is half the beat period.
Updated On: May 5, 2026
990 Hz
818.18 Hz
81.82 Hz
90 Hz
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Understanding Beat Phenomenon
- When two waves of close frequencies superpose, they produce beats due to interference.
- The beat frequency is given by: \[ f_{\text{beat}} = |f_1 - f_2| \]
- Here, \( f_1 = 128 \, \text{Hz} \), \( f_2 = 124 \, \text{Hz} \). Step 2: Maximum to Minimum Intensity
- One beat cycle consists of one maximum and one minimum.
- Time from maximum to adjacent minimum = half of beat period.
- Beat frequency: \[ f_{\text{beat}} = 128 - 124 = 4 \, \text{Hz} \]
- Beat period: \[ T_{\text{beat}} = \frac{1}{4} \, \text{s} \]
- Required time: \[ \Delta t = \frac{T_{\text{beat}}}{2} = \frac{1}{8} \, \text{s} \] Step 3: Final Answer
- Time between maximum and adjacent minimum intensity = \( \frac{1}{8} \, \text{s} \)
- When two waves of close frequencies superpose, they produce beats due to interference.
- The beat frequency is given by: \[ f_{\text{beat}} = |f_1 - f_2| \]
- Here, \( f_1 = 128 \, \text{Hz} \), \( f_2 = 124 \, \text{Hz} \). Step 2: Maximum to Minimum Intensity
- One beat cycle consists of one maximum and one minimum.
- Time from maximum to adjacent minimum = half of beat period.
- Beat frequency: \[ f_{\text{beat}} = 128 - 124 = 4 \, \text{Hz} \]
- Beat period: \[ T_{\text{beat}} = \frac{1}{4} \, \text{s} \]
- Required time: \[ \Delta t = \frac{T_{\text{beat}}}{2} = \frac{1}{8} \, \text{s} \] Step 3: Final Answer
- Time between maximum and adjacent minimum intensity = \( \frac{1}{8} \, \text{s} \)
Was this answer helpful?
0
0
Top TS EAMCET Physics Questions
- A wooden box lying at rest on an inclined surface of a wet wood is held at static equilibrium by a constant force $F$ applied perpendicular to the incline. If the mass of the box is $1\,kg$, the angle of inclination is $30^{\circ}$ and the coefficient of static friction between the box and the inclined plane is $0.2$, the minimum magnitude of $\vec{F}$ is (Use $ g = 10\,m/s^2$)
- A metre scale made of steel reads accurately at $25^{\circ} C$ . Suppose in an experiment an accuracy of $0.06\, mm$ in $1\,m$ is required, the range of temperature in which the experiment can be performed with this metre scale is (coefficient of linear expansion of steel is $ 11 \times 10^{-6} /^{\circ} \, C$ )
- Consider a solenoid carrying current supplied by a DC source with a constant emf containing iron core inside it. When the core is pulled out of the solenoid, the change in current will
- A parallel beam of light of intensity \(I_0\) is incident on a coated glass plate. If \(25\%\) of the incident light is reflected from the upper surface and \(50\%\) of light is reflected from the lower surface of the glass plate, the ratio of maximum to minimum intensity in the interference region of the reflected light is
- A thermocol box has a total wall area (including the lid) of $1.0 m ^{2}$ and wall thickness of $3 cm$. It is filled with ice at $0^{\circ} C$. If the average temperature outside the box is $30^{\circ} C$ throughout the day, the amount of ice that melts in one day is [Use $K_{\text {thermocol }}=0.03 W / mK$ $.L_{\text {fusion (ice) }}=3.00 \times 10^{5} J / kg ]$
View More Questions
Top TS EAMCET Thermodynamics Questions
The dimensions of four wires if the same material are given below. The increase in length is maximum in the wire of :
The Fahrenheit and Kelvin scales of temperature will have the same reading at a temperature of:
- If the ratio of densities of two substances is 5:6 and the ratio of their specific heat capacities is 3:5, then the ratio of heat energies required per unit volume so that the two substances can have same temperature rise is:
- The temperatures of the source and sink of a Carnot’s heat engine are 27$^\circ$C and 127$^\circ$C respectively. If the absolute temperature of the sink is decreased by 10\%, the efficiency of the engine:
- The temperatures of the source and sink of a Carnot’s heat engine are 27$^\circ$C and 127$^\circ$C respectively. If the absolute temperature of the sink is decreased by 10%, the efficiency of the engine:
View More Questions
Top TS EAMCET Questions
- A bag contains $5$ red balls, $3$ black balls and $4$ white balls are drawn at random. The probability that they are not of same colour is
- If $cosec\, \theta - \cot \theta = 2017$, then quadrant in which $\theta $ lies is
- If $a$ is a unit vector, then $| a \times \hat{ i }|^{2}+| a \times \hat{ j }|^{2}+| a \times \hat{ k }|^{2}=$
- $A$ straight line makes an intercept on the $Y$-axis twice as long as that on $X$-axis and is at a unit distance from the origin. Then the line is represented by the equations
- Let $S$ and $S'$ be the foci of an ellipse and B be one end of its minor axis. If $SBS'$ is an isosceles right angled triangle then the eccentricity of the ellipse is
View More Questions