Reflection, Refraction, and Light Properties

What type of image is formed in a plane mirror?

A virtual, upright, laterally inverted image the same size as the object.

Why can't a plane mirror form a real image?

Because reflected rays diverge, making the image appear behind the mirror.

What does lateral inversion mean?

The left and right sides of the image are swapped compared to the object.

Why do we use mirrors in vehicles?

To see behind safely using convex mirrors, which provide a wide field of view.

What is the critical angle, and what happens if light exceeds it?

The critical angle is the angle of incidence that produces an angle of refraction of 90°. If exceeded, total internal reflection occurs.

How does a glass block change the path of light?

Light bends toward the normal when entering (slower speed) and away from the normal when exiting (faster speed).

What is the refractive index, and how is it calculated?

The refractive index n is a measure of how much light bends. Formula: n = sin(i) / sin(r) (where i is the angle of incidence and r is the angle of refraction).

Why do objects appear bent or broken underwater?

Due to refraction; light changes speed as it moves between air and water, altering its path.

What is the order of colours in the visible spectrum from longest to shortest wavelength?

Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV).

Why is a prism better than a glass block for dispersion?

The triangular shape separates colours more effectively due to the different angles of refraction.

Why do we see rainbows after rain?

Sunlight disperses through water droplets in the air, acting like prisms to create a spectrum.

What are complementary colours of light?

Pairs of colours that produce white light when combined. Examples: Red + Cyan, Green + Magenta, Blue + Yellow.

What happens if you shine green light on a red object?

The object appears black because it cannot reflect green light.

Why do stage lights use different coloured filters?

To create specific moods or effects by allowing only certain colours to pass through.

How do we see colour on a TV screen?

By mixing red, green, and blue pixels at different intensities, creating a wide range of colours.

What primary colours of light combine to make magenta, cyan, and yellow?

Magenta: Red + Blue, Cyan: Green + Blue, Yellow: Red + Green.

Why do shadows appear blurry with multiple light sources?

Because multiple light sources produce overlapping penumbrae, causing softer, blurrier edges.

How does a pinhole camera produce an inverted image?

Light rays travel in straight lines; the top of the object forms the bottom of the image and vice versa.

What is the umbra and penumbra of a shadow?

Umbra: The darkest part with no light. Penumbra: The lighter, partially shaded area.

How do magnifying glasses use lenses to enlarge objects?

A convex lens magnifies objects when placed within its focal length, creating a virtual, upright, enlarged image.

What kind of image does a concave lens produce?

A virtual, upright, and diminished image.

Why do people wear glasses with concave or convex lenses?

Concave lenses: Correct short-sightedness (myopia). Convex lenses: Correct long-sightedness (hyperopia).

What is the relationship between the focal length and the curvature of a lens?

The shorter the focal length, the more curved the lens and the stronger its power.

Why should you avoid looking directly into a ray box?

The intense light can damage your eyes.

What should you do if the ray box gets too hot?

Turn it off and wait for it to cool to prevent burns.

Why is it important to conduct light experiments on a flat, stable surface?

To ensure accurate results and prevent equipment from falling or breaking.