Refraction and total internal reflectionEdexcel A-Level Physics: Flashcards
What these 13 flashcards ask
- Define refractive index.
- State Snell's law.
- What happens to the wavelength when light enters a denser medium?
- Which way does a ray bend entering a denser medium?
- Define the critical angle.
- State the formula for critical angle with air.
- State the two conditions for total internal reflection.
- What is the critical angle in glass of n = 1.50?
- What happens if the angle of incidence is slightly below the critical angle?
- What is the function of cladding on an optical fibre?
- Why does a diamond sparkle more than glass?
- In the core practical, what does the gradient of sin θ₁ against sin θ₂ give?
- Why should rays be drawn at a range of angles in the practical?
Exam questions on Refraction and total internal reflection
- A ray of light in air strikes the flat surface of a glass block of refractive index 1.50 at an angle of incidence of 40°. The speed of light in air is 3.00 × 10⁸ m s⁻¹ and the refractive index of air may be taken as 1.00.Calculate the angle of refraction of the ray inside the glass.2 marks
- A lamp at the bottom of a swimming pool shines light upwards on to the surface of the water. The refractive index of water is 1.33 and that of air is 1.00.Calculate the angle between the normal and the refracted ray in the air for the ray in (b).2 marks
- A student determines the refractive index of a rectangular glass block. She uses a ray box with a single slit to direct a narrow ray of light on to the block, and measures the angle of incidence θ₁ in air and the angle of refraction θ₂ inside the block for several different rays. She plots sin θ₁ against sin θ₂ and obtains a straight line through the origin with a gradient of 1.52.Explain why the graph is a straight line through the origin with a gradient equal to the refractive index of the glass, and calculate the speed of light in the block.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).