OCR A-Level Physics A H556
Practical Skills in the Written Papers
The Practical Endorsement
Physical Quantities and Units
Making Measurements and Analysing Data
Nature of Quantities
Motion
Forces in Action
Work, Energy and Power
Materials
Newton’s Laws of Motion and Momentum
Charge and Current
Energy, Power and Resistance
Electrical Circuits
Waves
Quantum Physics
Thermal Physics
Oscillations
Gravitational Fields
Astrophysics and Cosmology
Capacitors
Electric Fields
Electromagnetism
Nuclear and Particle Physics
Waves
Refraction and refractive index
- 3 things to know
- Papers 2 and 3
Overview
Recall questions on refraction and refractive index, n = c/v, the direction light bends between media, investigating refraction with rectangular and semi-circular blocks, and Snell's law.
What you need to know
Answer each one before you reveal it.
Define refraction.
Write the rearranged form of Snell's law used to find the angle of refraction.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define refraction.
Model answer
The change in direction of a wave when it passes from one medium to another due to a change in wave speed.
- 2
How is the refractive index of a material defined?
Model answer
The ratio of the speed of light in a vacuum to the speed of light in the material.
- 3
State the equation used to calculate the refractive index of a medium and define each symbol.
Model answer
n = c/v, where n is the refractive index, c is the speed of light in a vacuum, and v is the speed of light in the medium.
- 4
Calculate the refractive index when speed of light in vacuum = 3.00 × 10⁸ m s⁻¹, speed of light in medium = 1.43 × 10⁸ m s⁻¹.
Model answer
Refractive index = (3.00 × 10⁸) ÷ (1.43 × 10⁸) = 2.10.
- 5
In which direction does light bend when it travels from a less optically dense medium into a more optically dense medium?
Model answer
It bends towards the normal.
- 6
What happens to the direction of a light ray when it passes from a more optically dense medium into a less optically dense medium?
Model answer
It bends away from the normal.
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