11.5+Polarisation

IB Physics > Wave Phenomena
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POLARISATION
media type="custom" key="13527080" [|IB Polarisation qs with solutions.doc]
 * STANDING WAVE || DOPPLER || DIFFRACTION || RESOLUTION || POLARISATION ||
 * PRACTICE IB QUESTIONS**

Describe what is meant by polarized light. [|EM WAVE SIMULATION] - this one is plane-polarised POLARISED LIGHT: Light in which the oscillations are all in one plane. Only transverse waves can be polarised.

Describe polarization by reflection. POLARISATION BY REFLECTION: Reflected light is partly plane-polarised depending on the incident angle. [|POLARISED LIGHT OFF WATER SIMULATION] This may be illustrated using light or microwaves. The use of polarized sunglasses should be included. POLARISED SUNGLASSES: The filters are polarisers and block glare (from light reflected from water for example).

State and apply Brewster’s law [|BREWSTER LAW SIMULATION]

When the incident angle is the Brewster angle, the angle between the reflected ray and transmitted ray is a right angle.



Explain the terms polarizer and analyser [|POLARISERS SIMULATION] [|POLARISATION FILTERS SIMULATION] When light passes through two polarising filters, the first is called the polariser: it polarises the incident light. The second filter is called the analyser: it can help to determine whether the incident light is polarised and at what angle.

Calculate the intensity of a transmitted beam of polarized light using Malus’ law. For the intensity I of the transmitted light through a polariser where θ is the angle between the incident plane of polarisation and the plane of the polariser and Io is the intensity of the incident light. Intensity is measured in watt per meter squared.

Describe what is meant by an optically active substance. OPTICALLY ACTIVE SUBSTANCE: rotates the plane of polarisation of light eg sugar solutions, quartz. For a solution, the more concentrated it is, the greater the angle of rotation. Students should be aware that such substances rotate the plane of polarization. Describe the use of polarization in the determination of the concentration of certain solutions.

Outline qualitatively how polarization may be used in stress analysis. Stress can make a substance optically active and colours can be seen when polarised light passes through them. Outline qualitatively the action of liquid-crystal displays (LCDs). Aim 8: The use of LCD screens in a wide variety of different applications/devices can be mentioned. Solve problems involving the polarization of light. Solve problems involving the polarization of light.