Answer: a) Red

Explanation: Red light has the longest wavelength of visible light, while violet light has the shortest.

Answer: b) Concave lens

Explanation: A concave lens is thinner at the center and thicker at the edges, which causes light rays to diverge. This helps to correct the focus of the eye in people who are nearsighted.

Answer: d) Yellow

Explanation: The primary colors of light are red, green, and blue. Yellow is a secondary color that is produced by combining red and green light.

Answer: a) The speed of light is constant in all media.

Explanation: The speed of light is a fundamental constant of nature and is always the same in a vacuum, air, water, glass, or any other medium.

Answer: a) 299,792,458 m/s

Explanation: The speed of light in a vacuum is a fundamental constant of nature and is approximately 299,792,458 meters per second.

Answer: a) Interference

Explanation: Interference is the phenomenon by which light waves combine to create areas of constructive interference, where the waves reinforce each other, and areas of destructive interference, where the waves cancel each other out.

Answer: d) Change in speed

Explanation: Refraction is the bending of light as it passes through a medium with a different density, which causes a change in its speed.

Answer: c) Blue

Explanation: The wavelength of blue light is shorter than the wavelengths of red, green, and yellow light. Blue light has a wavelength of approximately 400-500 nanometers, while red light has a wavelength of approximately 620-750 nanometers.

Answer: d) Emission

Explanation: Emission is the process by which light is produced by an atom when an electron moves from a higher energy level to a lower energy level and releases energy in the form of a photon.

Answer: a) Hertz

Explanation: The frequency of light is measured in hertz (Hz), which is a unit of measurement for cycles per second.