Question 1:

Diagram A is the correct representation.

Here is why:

• Refraction: When light moves from a less dense medium (air) to a more dense medium (plastic), it bends towards the normal (the dashed line). Diagram A shows this correctly at the flat surface.

• The Curved Surface: In all four diagrams, the ray exits through the curved boundary along a radius. Since the ray is perpendicular to the boundary at that point, it does not bend and continues in a straight line.

Eliminating Others:

• B shows the light bending away from the normal when entering the plastic.

• C shows light traveling along the normal but then bending, which violates Snell's Law.

• D shows light reflecting, not refracting, as if the surface were a mirror.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 2:

The correct answer is D.
When light enters a denser medium (plastic) from a less dense medium (air), it slows down and bends towards the normal line.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 3:

The correct answer is a) n=sin⁡i/sin⁡r.

Snell’s Law relates the angle of incidence i and angle of refraction r when light passes from one medium to another. For light entering a medium from air (or vacuum), the refractive index n of the medium is defined as the ratio of sin⁡i to sin⁡r.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 4:

The correct answer is C. The refractive index of the substance.

In Snell’s Law (n=sin ⁡i/sin ⁡r), n represents the refractive index, which measures how much light slows down and bends when entering a material.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 5:

The correct answer is A. 1.52.

Using Snell’s Law:
n=sin⁡40∘sin⁡25∘≈0.6428/0.4226≈1.52.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 6:

The correct answer is b) sin ⁡c=1/n.

This is the critical angle formula, where c is the critical angle and n is the refractive index of the denser medium (relative to the less dense medium).

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 7:

Correct Answer: A

Explanation:
Total internal reflection (TIR) occurs when a light ray traveling through a denser medium (glass) hits the boundary of a less dense medium (air) at an angle greater than the critical angle.

Diagram A (Correct):
The light ray enters the prism perpendicular to the first surface without bending. It hits the diagonal internal surface (hypotenuse) at a 45° angle, which exceeds the critical angle for glass (~42°). This causes it to reflect entirely inside the glass and exit straight through the bottom surface.

Diagram B (Incorrect):
The path shows light reflecting incorrectly relative to the incoming direction and internal boundary.

Diagram C (Incorrect):
The ray enters normally but reflects off a boundary geometry that does not support total internal reflection in this path.

Diagram D (Incorrect):
The internal geometry and angle of incidence do not match a valid 90° total internal reflection path.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 8:

The correct answer is A. 39°.

Using the critical angle formula:

sin⁡ c=1/n=1/1.6=0.625

c=arcsin⁡(0.625)≈38.7∘≈ 39°

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 9:

The correct answer is C. n = 1.5.

For total internal reflection at an incident angle of 45°, the critical angle c must be ≤ 45°.
Using sin⁡ c=1/n, we need 1/n≤sin⁡45°≈0.7071, so n≥1.414.
Among the given values, the smallest n that meets this is 1.5.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 10:

Optical fibres are thin, flexible strands of glass (or plastic) that guide light along their length using total internal reflection.

• The core of the fibre has a higher refractive index than the surrounding cladding.

• When light enters the fibre at a suitable angle, it strikes the core-cladding boundary at an angle greater than the critical angle, causing total internal reflection.

• This allows the light to bounce along the fibre with very little loss, even around bends.

The other options are not standard terms:

• Light cables – not the technical name.

• Laser channels – not used.

• EM wave cables – too broad; refers to any cable carrying electromagnetic waves (e.g., coaxial cables for radio waves), not specifically glass strands using TIR.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.