8th Chapter Solved Exercise MCQs Of FSc First Year Physics

8th Chapter Solved Exercise MCQs of FSc First Year Physics is a helpful resource for students preparing for exams, featuring solved multiple-choice questions. Each MCQ comes with a clear explanation, making it easier to understand the correct answers. Use this resource to enhance your studies and feel ready for your exams.

8th chapter solved MCQs with explanation

1. Longitudinal waves can not pass through:

(a) Liquid

(b) Solids

(c) Vacuum

(d) Gases

Explanation: Longitudinal waves require a medium to propagate. They cannot travel through a vacuum, which is a region devoid of matter.

2. When two identical waves superimposed, the velocity of the resultant wave:

(a) Remains unchanged

(b) Decreases

(c) Increases

(d) Is zero

Explanation: The superposition of two identical waves can result in constructive interference, which increases the amplitude and velocity of the resultant wave.

3. Waves produced in organ pipes are:

(a) Transverse waves

(b) Longitudinal waves

(c) EM wave

(d) All of above

Explanation: Organ pipes produce sound waves, which are longitudinal waves that propagate through the air.

4. Speed of sound in summer than in winter.

(a) Increased

(b) Decreased

(c) Remains same

(d) Cannot tell

Explanation: The speed of sound in air depends on temperature. Generally, the speed of sound increases with temperature. However, other factors like humidity can also affect the speed, so it’s not always possible to determine whether the speed will increase or decrease without more information.

5. Newton calculated speed of sound using

(a) Adiabatic process

(b) Isothermal process

(c) Both (a) and (b)

(d) None of these

Explanation: Newton’s original calculation for the speed of sound assumed an isothermal process. However, the correct process is adiabatic, which takes into account the compression and heating of the air during the propagation of sound waves.

6. Speed of sound in hydrogen is times its speed in oxygen.

(a) 2

(b) 4

(c) 4

(d) 16

Explanation: The speed of sound in a gas is inversely proportional to the square root of its molar mass. Hydrogen has a much lower molar mass than oxygen, so the speed of sound in hydrogen is approximately 4 times its speed in oxygen.

7. Error in calculation of Newton’s formula for speed of sound is about:

(a) 16%

(b) 27%

(c) 10%

(d) 35%

Explanation: Newton’s original formula for the speed of sound underestimated the actual speed by about 35%. This error was corrected by Laplace, who took into account the adiabatic nature of sound propagation.

8. The frequency range of human ear is:

(a) 20 Hz – 20 kHz

(b) 20 Hz – 20 MHz

(c) 20 Hz – 200 Hz

(d) 200 Hz – 2 KHz

Explanation: The human ear is sensitive to sound waves with frequencies between approximately 20 Hz and 20,000 Hz.

9. Beats are the results of:

(a) Destructive interference

(b) Diffraction of sound waves

(c) Constructive and destructive interference

(d) None of these

Explanation: Beats are produced when two sound waves of slightly different frequencies interfere with each other. The resulting interference pattern causes a periodic variation in the amplitude of the sound wave, creating a pulsating sensation known as beats.

10. If the time required for the tuning fork to make one complete vibration, the wave in air will travel a distance equal to:

(a) λ

(b) 2λ

(c) λ/2

(d) 2λ

Explanation: The wavelength of a wave is the distance traveled by the wave in one period. Therefore, if the tuning fork takes one complete vibration, the wave will travel a distance equal to two wavelengths (2λ).

11. The term which can tell us the stage of vibration of the particles of the medium is called:

(a) Wavelength

(b) Phase

(c) Amplitude

(d) Time period

Explanation: The phase of a wave represents the position of a particle in the wave cycle relative to a reference point. It tells us the stage of vibration of the particles.

12. It is common characteristics of all types of wave motion without the transport of particles.

(a) Energy transferred

(b) Mass decreased

(c) Particles

(d) Drown

Explanation: A common characteristic of all types of wave motion is the transfer of energy without the transport of matter.

13. When a string, which is tied at both ends is plucked from the centre of waves, produces:

(a) Standing waves

(b) Electromagnetic waves

(c) Transverse waves

(d) Longitudinal waves

Explanation: When a string is plucked from the center, it produces standing waves, which are formed by the superposition of two waves traveling in opposite directions.

14. In a stretched string, if speed of the wave is doubled, the tension will be:

(a) 2

(b) 4

(c) 4

(d) 6

Explanation: The speed of a wave on a stretched string is proportional to the square root of the tension. Doubling the speed requires quadrupling the tension.

15. frequency of a stretched string is proportional to the:

(a) Tension

(b) Linear density

(c) Reciprocal of length

(d) Square of tension

Explanation: The frequency of a stretched string is directly proportional to the square root of the tension.

16. A string fixed at two ends vibrates in one segment. The standing wave pattern is:

(a) First overtone

(b) Second overtone

(c) Fundamental

(d) Second overtone

Explanation: A string vibrating in one segment is in its fundamental mode, which is the lowest frequency standing wave pattern.

17. Two sounds of the same frequency in air must have same:

(a) Amplitude

(b) Loudness

(c) Intensity

(d) Wavelength

Explanation: Sounds of the same frequency have the same wavelength. However, their amplitude, loudness, and intensity can vary.

18. Which of the following phenomenon can not take place with sound waves?

(a) Diffraction

(b) Reflection

(c) Interference

(d) Polarization

Explanation: Polarization is a property of transverse waves and cannot occur with longitudinal waves like sound waves.

 19. Presence of moisture in air:

(a) Increases speed of sound

(b) Decreases speed of sound

(c) May increase/decrease the sound velocity

(d) Does not affect the motion of source and observer

Explanation: The presence of moisture in air can affect the speed of sound, but the exact effect depends on various factors like temperature and humidity.

 20. Doppler’s shift measure the change in:

(a) Intensity

(b) Frequency

(c) Velocity

(d) Wavelength

Explanation: The Doppler shift is a change in the observed frequency of a wave due to relative motion between the source and the observer. It is used to measure the velocity of the source or observer.