Question 1: Refraction is the bending of light as it passes from one medium to another due to a change in its speed. This phenomenon occurs because light travels at different speeds in different materials, such as air, glass, or water.

Answer: Refraction is the bending of light when it passes from one medium to another because of a change in its speed.

Question 1: Define the term 'refractive index'.

Answer: Refractive index is a measure of how much light slows down in a particular medium compared to air.

Question 2: Explain why light bends towards the normal when passing from air into glass.

Answer: Because light slows down when entering glass, causing it to bend towards the normal line.

Question 1: A ray of light passes from air (refractive index = 1.00) into water (refractive index = 1.33) at an angle of 30°. Calculate the angle of refraction in water. (Use Snell's Law: n₁ sin θ₁ = n₂ sin θ₂)

Answer: 20.3°

Question 2: If the angle of incidence in air is 45°, what is the critical angle for total internal reflection when passing into water? (Refractive index of water = 1.33)

Answer: 48.75°

Question 1: Describe a simple experiment to demonstrate the refraction of light using a glass block and a ray of light. Include the key variables to control and safety precautions.

Answer: Use a glass block and a ray of light from a source like a laser or torch. Shine the light at an angle onto the block, observe the bending at the interface. Variables include the angle of incidence, medium type, and light source intensity. Safety precautions include avoiding direct eye exposure to laser beams and handling glass carefully to prevent breakage.

Question 1: A swimming pool appears shallower than it actually is because of refraction. Explain the physics behind this observation.

Answer: Refraction causes light rays from the bottom to bend when passing from water to air, making the bottom appear closer to the surface, thus creating an optical illusion of shallowness.

Question 2: Identify a practical application of refraction in technology or industry.

Answer: Refraction is used in fibre optic cables to transmit data over long distances with minimal loss.

Question 1: Explain how the change in light speed causes the bending of light when passing from air into water, and how this principle is utilised in the design of optical devices such as lenses.

Answer: When light enters water from air, it slows down due to the higher refractive index, causing it to bend towards the normal. This change in direction and speed is described by Snell's Law. Optical devices like lenses use this principle to focus or diverge light, enabling magnification, correction of vision, and various imaging technologies.