Multiple Choice Questions
Physics: Waves
Topic: Waves, Sound, and Light
Grade: 10
Question 1:
Which of the following statements is true about longitudinal waves?
A) They can only travel through solids
B) They can only travel through liquids
C) They can travel through both solids and liquids
D) They cannot travel through any medium
Answer: C) They can travel through both solids and liquids
Explanation: Longitudinal waves are a type of mechanical wave that travel by compressing and expanding the medium. Unlike transverse waves, they do not require a specific medium to travel and can move through both solids and liquids. A common example of a longitudinal wave is sound waves, which can travel through air, water, and solids.
Example:
Simple: When you speak, your vocal cords produce sound waves that travel through the air and reach the listener\’s ears.
Complex: During an earthquake, the movement of tectonic plates generates seismic waves that propagate through the Earth\’s interior.
Question 2:
Which of the following properties of a wave determines its pitch?
A) Amplitude
B) Frequency
C) Wavelength
D) Speed
Answer: B) Frequency
Explanation: The pitch of a sound wave refers to how high or low the sound is perceived. It is directly related to the frequency of the wave. Frequency is the number of complete cycles or vibrations of a wave that occur in one second. Higher frequencies result in higher pitches, while lower frequencies result in lower pitches.
Example:
Simple: When you pluck a guitar string tightly, it produces a high-pitched sound because the string vibrates at a high frequency.
Complex: Dolphins use echolocation to navigate and locate objects underwater. They emit high-frequency clicks and listen for the echoes to determine the distance and location of objects.
Question 3:
Which of the following statements is true about the speed of light in different mediums?
A) Light travels faster in liquids than in gases
B) Light travels faster in gases than in solids
C) Light travels at the same speed in all mediums
D) Light does not travel in any medium
Answer: C) Light travels at the same speed in all mediums
Explanation: The speed of light in a vacuum is constant and approximately 3.00 x 10^8 meters per second. When light enters a different medium, such as air, water, or glass, its speed changes, but it remains constant within that medium. The change in speed is caused by the interaction of light with the atoms or molecules in the medium.
Example:
Simple: When a beam of light enters water, it slows down due to the interaction with water molecules, but it still maintains a constant speed within the water.
Complex: The phenomenon of total internal reflection occurs when light traveling in a denser medium, such as glass, strikes the boundary with a less dense medium, such as air, at an angle greater than the critical angle. This causes the light to be completely reflected back into the denser medium.
Question 4:
Which of the following devices uses a lens to form images by refracting light?
A) Telescope
B) Microscope
C) Binoculars
D) Camera
Answer: D) Camera
Explanation: Cameras use lenses to focus and direct light onto a photosensitive surface, such as film or an image sensor. The lens refracts the incoming light, allowing it to converge or diverge to form a clear image on the surface. The specific type of lens used in a camera depends on the desired focal length and magnification.
Example:
Simple: When you use a magnifying glass to focus sunlight onto a piece of paper, the lens refracts the light, causing it to converge and create a small bright spot that can ignite the paper.
Complex: The Hubble Space Telescope uses multiple lenses and mirrors to capture and focus light from distant galaxies. These lenses and mirrors correct for aberrations and produce high-resolution images of celestial objects.
Question 5:
Which color of light has the shortest wavelength?
A) Red
B) Blue
C) Green
D) Yellow
Answer: B) Blue
Explanation: The color of light is determined by its wavelength. Blue light has a shorter wavelength compared to red, green, and yellow light. The shorter the wavelength, the higher the energy and frequency of the light. This is why blue light is more energetic and can cause more damage to the eyes compared to other colors.
Example:
Simple: The blue sky appears blue because the shorter blue wavelengths are scattered more by the Earth\’s atmosphere, while the longer red wavelengths are scattered less.
Complex: Ultraviolet (UV) light, which is invisible to the human eye, has even shorter wavelengths than blue light. UV light is responsible for causing sunburns and can be harmful to the skin and eyes if exposed for long periods.