Simple Harmonic Motion (SHM) and Waves form the foundation of oscillatory motion and wave phenomena in physics. This chapter explains how restoring forces cause periodic motion in systems like springs, pendulums, and balls in bowls. It also explores wave types, properties, and behaviors such as reflection, refraction, diffraction, and damping. Understanding SHM and wave mechanics helps explain sound, light, and energy transfer processes in nature.
Note: In the Punjab and Sindh Board textbooks, this topic appears as Chapter 10: Simple Harmonic Motion and Waves. It is presented here as Chapter 1 in the merged Class 10 Physics sequence for your convenience.
1. Which condition is essential for an object to execute Simple Harmonic Motion?
- A. Constant velocity
- B. Acceleration directly proportional to displacement and directed towards mean position β
- C. Constant acceleration
- D. Velocity proportional to displacement
Explanation: In SHM, acceleration is always proportional to displacement from the mean position and directed towards it, acting as a restoring force.
2. In the formula T = 2Οβ(l/g) for a simple pendulum, the time period depends on:
- A. Length of the pendulum and acceleration due to gravity β
- B. Mass of the bob
- C. Amplitude of oscillation
- D. Air resistance
Explanation: The period of a simple pendulum is independent of mass and amplitude for small oscillations; it depends on length and g.
3. What is the role of the restoring force in SHM?
- A. To maintain constant velocity
- B. To bring the object back towards the mean position β
- C. To increase the amplitude
- D. To keep the object at rest
Explanation: Restoring force always acts towards the mean position and is responsible for the oscillatory nature of SHM.
4. Which type of wave requires a medium for propagation?
- A. Mechanical wave β
- B. Electromagnetic wave
- C. Gamma rays
- D. X-rays
Explanation: Mechanical waves need a material medium (solid, liquid, or gas) to propagate, unlike electromagnetic waves which can travel in vacuum.
5. In a transverse wave, the particles of the medium:
- A. Move along the direction of wave propagation
- B. Move perpendicular to the direction of wave propagation β
- C. Remain stationary
- D. Move in circular paths
Explanation: In transverse waves, the displacement of particles is at right angles to the direction in which the wave travels.
6. The wavelength of a wave is defined as:
- A. The distance between a crest and the mean position
- B. The distance between two consecutive crests or troughs β
- C. The time taken to complete one oscillation
- D. The height of a wave
Explanation: Wavelength is the spatial period of the waveβthe distance over which the wave’s shape repeats.
7. If a wave has a frequency of 5 Hz and a wavelength of 2 m, its speed is:
- A. 2.5 m/s
- B. 5 m/s
- C. 10 m/s β
- D. 15 m/s
Explanation: Wave speed v = f Γ Ξ» = 5 Γ 2 = 10 m/s.
8. Which property of a wave changes when it enters a different medium at an angle?
- A. Frequency
- B. Wavelength β
- C. Amplitude only
- D. Crest height
Explanation: In refraction, wave speed and wavelength change, but frequency remains constant.
9. Diffraction of waves is more pronounced when:
- A. Wavelength is much smaller than the obstacle
- B. Wavelength is comparable to the obstacle size β
- C. Wavelength is zero
- D. The obstacle is transparent
Explanation: Maximum diffraction occurs when obstacle or slit size is similar to the wavelength of the wave.
10. Damping in oscillations results in:
- A. Increase in amplitude over time
- B. Constant amplitude
- C. Gradual decrease in amplitude β
- D. Increase in frequency
Explanation: Damping dissipates energy, causing amplitude to reduce gradually with time.
11. Which wave property determines the pitch of a sound?
- A. Amplitude
- B. Frequency β
- C. Wavelength
- D. Wave speed
Explanation: Higher frequency corresponds to higher pitch in sound waves.
12. The point of maximum displacement in a transverse wave is called:
- A. Crest β
- B. Trough
- C. Node
- D. Antinode
Explanation: In transverse waves, crests are the highest points above the mean position.
13. In longitudinal waves, regions of high particle density are called:
- A. Compressions β
- B. Rarefactions
- C. Nodes
- D. Antinodes
Explanation: Compressions are areas where particles are closer together, resulting in higher pressure.
14. Which instrument is commonly used to study water wave behavior in a lab?
- A. Oscilloscope
- B. Spring balance
- C. Ripple tank β
- D. Vernier caliper
Explanation: A ripple tank produces and displays wave patterns, allowing observation of reflection, refraction, and diffraction.
15. In the equation v = fΞ», what does Ξ» represent?
- A. Frequency
- B. Speed
- C. Wavelength β
- D. Amplitude
Explanation: Ξ» (lambda) denotes the wavelength, the distance between two identical points on consecutive cycles of a wave.