BRAINCAKEOptics
Revision notes for Optics in Edexcel Physics (8PH0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- RefractionRefraction is the change in direction of a wave when it passes from one medium into another and changes speed.
- Snell's LawSnell's law links the angles on either side of a boundary to the refractive indices of the two materials: n1 sin θ1 = n2 sin θ2 n1 and θ1 are the…
- Investigating Refractive IndexThis practical measures the refractive index of glass using a rectangular glass block and a ray box.
- DispersionDispersion is the splitting of white light into its separate colours, forming a spectrum.
- Total Internal ReflectionWhen light travels from a material with a higher refractive index to one with a lower refractive index (for example from glass to air), it bends…
- Investigating Total Internal ReflectionThe critical angle of a material, and so its refractive index, can be measured using a semicircular glass block and a ray box.
- Applications of Total Internal ReflectionTotal internal reflection (TIR) reflects all of the light, with no loss by refraction, so it has many uses.
- Concave LensesA concave lens is thinner at its centre than at its edges.
- Convex LensesA convex lens is thicker at its centre than at its edges.
- The Power of a LensThe power of a lens measures how strongly it converges or diverges light.
- The Power of Twin LensesWhen two thin lenses are placed in contact, they act like a single lens.
- Forming an ImageA lens forms an image of an object.
- Image CalculationsThe position of the image formed by a thin lens can be calculated with the lens equation: 1/u + 1/v = 1/f u is the distance from the lens to the…
- MagnificationMagnification tells you how many times bigger (or smaller) the image is than the object: m = image height / object height = v / u where v is the…
- Plane PolarisationLight is a transverse wave: the oscillations (of the electric and magnetic fields) are perpendicular to the direction in which the wave travels and…
- Polarising FiltersA polarising filter (such as Polaroid) contains long-chain molecules lined up in one direction.
- Polarisation by Reflection and RefractionPolarising filters are not the only way to polarise light.
- Exam-style Question 1Question (a) State what is meant by plane polarised light.
- Exam-style Question 2Question Unpolarised light of intensity 80 W m-2 is incident on a polarising filter P.
- Exam-style Question 3Question An angler standing on a river bank finds it hard to see fish in the water because of glare from the water surface.
- Exam-style Question 4Question A converging lens has a focal length of 20 cm.
On the specification
- Topic 5: Waves and Particle Nature of Light