Light and Sound Quiz

Which of the following correctly explains why sound waves cannot travel through space?

1. Space has high air pressure that absorbs sound
2. Space lacks a medium for sound wave vibrations
3. Sound waves lose energy before reaching space
4. The temperature in space is too low for sound waves to propagate

Answer: (b) Space lacks a medium for sound wave vibrations

Two students argue about why the sky looks red during sunset. One says it’s due to scattering, while the other says it’s due to refraction. Who is correct?

1. First student, because shorter wavelengths scatter more
2. Second student, because refraction bends light more at sunset
3. Both are correct, but scattering plays a dominant role
4. Neither is correct; it is due to reflection from the atmosphere

Answer: (c) Both are correct, but scattering plays a dominant role

In a dark room, a person sees a sudden bright flash of light. Which part of the eye will react first, and what will it do?

1. Cornea; It bends light to reduce intensity.
2. Retina; It adjusts the sensitivity of rod cells.
3. Iris; It contracts the pupil to reduce light entry.
4. Lens; It becomes thicker to prevent excess light.

Answer: (c) Iris; It contracts the pupil to reduce light entry.

A music producer is designing a new speaker system. What should they do to ensure the bass (low-frequency sounds) is heard clearly?

1. Use smaller speakers that produce shorter wavelengths
2. Use larger speakers that can amplify long wavelengths
3. Increase the speed of sound to make bass travel faster
4. Increase the pitch to enhance lower frequencies

Answer: (b) Use larger speakers that can amplify long wavelengths

Two students argue about the loudness of sound. One says it depends on frequency, while the other claims it depends on amplitude. Who is correct and why?

1. The first student is correct because higher frequency means more energy.
2. The second student is correct because greater amplitude means higher energy.
3. Both are correct because both frequency and amplitude affect loudness equally.
4. Neither is correct because loudness depends only on the speed of sound.

Answer: (b) The second student is correct because greater amplitude means higher energy.

An object is placed at infinity in front of a convex lens. Where will the image be formed and what will be its characteristics?

1. Beyond 2F, virtual, upright, and reduced
2. At 2F, real, upright, and magnified
3. Between F and the optical centre, virtual, upright, and magnified
4. At the focus (F), real, inverted, and highly diminished

Answer: (d) At the focus (F), real, inverted, and highly diminished

A photographer adjusts the focal length of a camera lens to capture a distant mountain. She later brings the camera closer to a flower and readjusts the lens to focus on it. What adjustment did she make to focus on the flower compared to the mountain?

1. She increased the focal length of the lens
2. She decreased the focal length of the lens
3. She moved the lens closer to the image sensor
4. She moved the lens farther from the image sensor

Answer: (d) She moved the lens farther from the image sensor

An elderly person struggles to read small letters in a book when holding it close, but can see distant objects clearly. He visits an eye doctor and is advised to use convex lenses. Which of the following statements best explains his condition?

1. He has myopia, and his eyeball is elongated, causing light to focus in front of the retina.
2. He has hypermetropia, and his eyeball is too short, causing light to focus behind the retina.
3. He has presbyopia, caused by reduced flexibility of the eye lens due to aging.
4. He has astigmatism, where the cornea's uneven curvature affects vision.

Answer: (c) He has presbyopia, caused by reduced flexibility of the eye lens due to aging.

A light ray enters a glass slab of refractive index 1.5 at an angle of 30°. A part of the ray is refracted inside, while another part is reflected back into the air. What will be the angle of reflection for the reflected ray?

1. 30°
2. 45°
3. 60°
4. 90°

Answer: (a) 30°

A convex lens of focal length 20 cm is placed 50 cm in front of a plane mirror. An object is positioned 40 cm in front of the convex lens. Which of the following statements is/are correct? 1. The final image is real and inverted. 2. The image formed by the lens alone is at 40 cm behind the lens. 3. If the distance between the lens and the mirror is reduced to 30 cm, the final image position remains unchanged.

1. 1 and 2 only
2. 2 and 3 only
3. 3 only
4. 1, 2, and 3

Answer: (a) 1 and 2 only