Light: Practice Questions

A person stands \(2.0\text{ m}\) in front of a vertical plane mirror. What is the distance between the person and their image?

The speed of light in air is \( 3.0 \times 10^8\text{ m/s} \). The speed of light in a specific type of glass is \( 2.0 \times 10^8\text{ m/s} \). What is the refractive index of this glass?

A ray of light is incident on a plane mirror, making an angle of incidence of \( 25^\circ \). The mirror is then rotated by \( 10^\circ \) about the point of incidence such that the angle of incidence decreases. What is the new angle between the incident ray and the reflected ray?

A student writes the word PHYSICS on a card and holds it in front of a vertical plane mirror. Which row correctly describes the characteristics of the image formed?

A boy stands \( 2.0\ \mathrm{m} \) in front of a vertical plane mirror. Which statement correctly describes the characteristics of the image formed?

Define the term normal as used in the context of a light ray striking a plane mirror.

State the region of the electromagnetic spectrum used primarily for short-range communication, such as remote controllers for televisions, and describe one potential harmful effect of excessive exposure to infrared radiation.

Explain the optical function of a diverging lens in the correction of short-sightedness (myopia), specifically describing how the lens modifies the convergence of light rays before they enter the eye to ensure a clear image is focused on the retina.

(a) A converging lens has a focal length \(f\) of \(2.0 \text{ cm}\). An object O is placed \(1.5 \text{ cm}\) from the centre of the lens.

Describe the characteristics of the image formed (i.e., real/virtual, inverted/upright, enlarged/diminished).

(b) Explain, by referencing the required object position relative to the focal length, how a converging lens is used as a magnifying glass.

(c) If the lens produces a virtual image that is \(6.0 \text{ cm}\) tall when the object is \(2.0 \text{ cm}\) tall, calculate the linear magnification produced by the lens.

A ray of monochromatic light travels through a glass prism as part of an optics experiment. The prism is made of glass with a refractive index of \(n = 1.62\).

(a) The speed of light in a vacuum is \(3.00 \times 10^8 \text{ m/s}\). Calculate the speed of light in the glass prism.

(b) The ray of light hits the boundary between the glass and air from inside the prism. Calculate the critical angle \(c\) for this glass-air boundary.

(c) The light ray approaches the boundary at an angle of incidence of \(45.0^{\circ}\). State and explain what happens to the light ray at the boundary. Your explanation must include a comparison with the value calculated in part (b).

(d) An object is placed \(12.0 \text{ cm}\) from a thin converging lens of focal length \(8.0 \text{ cm}\).
(i) Determine the distance of the image from the centre of the lens.
(ii) State the three characteristics of the image formed.