BRAINCAKEOptics
Revision notes for Optics in Edexcel Physics (8PH0). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- 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.