Practice Waves MCQs for JSMU Karachi Entry Test Physics — topic-wise sets with solved answers.
Q1. A wave is produced on a string by moving one end up and down. What type of wave is this?
Answer: Transverse wave
Explanation: The wave is transverse because particle displacement is perpendicular to wave propagation. Option A is incorrect because longitudinal waves have parallel displacement.
Q2. The distance between two consecutive crests in a wave is 4 cm. What is the wavelength?
Answer: 4 cm
Explanation: Wavelength is the distance between consecutive crests. Option A is incorrect because it is half the given distance.
Q3. A sound wave travels through air at 20°C. If its frequency is 500 Hz, what is its approximate wavelength?
Answer: 0.68 m
Explanation: Using v = fλ, with v ≈ 340 m/s at 20°C, we get λ = v/f = 340/500 = 0.68 m. Option C is incorrect due to wrong calculation.
Q4. What is the primary characteristic that distinguishes a stationary wave from a progressive wave?
Answer: Energy transfer
Explanation: Stationary waves do not transfer energy, whereas progressive waves do. Option A is incorrect because amplitude can vary in both types.
Q5. When a wave passes from one medium to another, which property remains unchanged?
Answer: Frequency
Explanation: Frequency remains constant when a wave passes from one medium to another. Option A is incorrect because speed changes with medium.
Q6. In a ripple tank, waves travel from deep water to shallow water. What happens to their wavelength?
Answer: Decreases
Explanation: As waves enter shallow water, their speed decreases, and so does their wavelength. Option A is incorrect because wavelength does not increase.
Q7. The superposition principle is applicable to all types of waves. What does it imply?
Answer: The resultant displacement is the sum of individual displacements
Explanation: The superposition principle states that the resultant displacement is the vector sum of individual displacements. Option B is a partial truth but not the full implication.
Q8. A string fixed at both ends produces a standing wave. What is the minimum distance between two nodes?
Answer: λ/2
Explanation: The distance between two consecutive nodes in a standing wave is λ/2. Option A is incorrect because it is the distance from a node to an antinode.
Q9. Beats are formed when two waves of slightly different frequencies overlap. What is the beat frequency?
Answer: Difference of the frequencies
Explanation: Beat frequency is the absolute difference between the two frequencies. Option A is incorrect because it represents the sum, not the difference.
Q10. A tuning fork produces a sound wave. If it is held near a closed pipe, what happens to the air inside the pipe?
Answer: It vibrates at the same frequency as the tuning fork
Explanation: The air inside the pipe vibrates at the same frequency due to forced vibration. Option C is incorrect because the frequency is the same, not different.
Q11. Doppler shift occurs when there is relative motion between the source and the observer. What changes?
Answer: Frequency
Explanation: The Doppler effect results in a change in the observed frequency. Option B is incorrect because wavelength also changes but the primary effect is on frequency.
Q12. In a stretched string, the speed of a transverse wave depends on which of the following?
Answer: Tension and mass per unit length
Explanation: The speed of a transverse wave in a string depends on tension and mass per unit length. Option B is incorrect because length is not a factor in the speed equation.
Q13. What is the condition for two waves to be coherent?
Answer: Same frequency and constant phase difference
Explanation: Coherent waves have the same frequency and a constant phase difference. Option B is incorrect because amplitude is not a requirement for coherence.
Q14. When the intensity of a wave is increased, what happens to its amplitude?
Answer: Increases
Explanation: Intensity is proportional to the square of the amplitude, so increasing intensity increases amplitude. Option A is incorrect because amplitude does not decrease.
Q15. A wave has an amplitude of 2 cm and a frequency of 100 Hz. If its amplitude is doubled, what happens to its energy?
Answer: Quadruples
Explanation: Energy is proportional to the square of the amplitude, so doubling amplitude quadruples energy. Option B is incorrect because energy does not just double.
Q16. The phenomenon where waves bend around obstacles is known as?
Answer: Diffraction
Explanation: Diffraction is the bending of waves around obstacles. Option A is incorrect because reflection involves a change in direction at a surface.
Q17. Two waves of equal amplitude and frequency overlap in phase. What is the resultant amplitude?
Answer: Twice the individual amplitude
Explanation: When waves overlap in phase, their amplitudes add up, resulting in twice the individual amplitude. Option B is incorrect because the amplitude is doubled, not the same.
Q18. What is the condition for destructive interference to occur?
Answer: Path difference is an odd number of half-wavelengths
Explanation: Destructive interference occurs when the path difference is an odd multiple of λ/2. Option A is incorrect because it results in constructive interference.
Q19. The speed of sound in air at 0°C is approximately?
Answer: 331 m/s
Explanation: The speed of sound in air at 0°C is approximately 331 m/s. Option A is incorrect because it is slightly less than the correct value.
Q20. A sound wave is reflected back to its source. What type of interference occurs at the source?
Answer: Constructive interference
Explanation: The reflected wave and the original wave are in phase at the source, resulting in constructive interference. Option B is incorrect because the phase difference is zero.
Loading...