Chapter 4.4 Flashcards
Law of reflection
The angle of incidence is equal to the angle of reflection. The reflected and incident days and the normal to the surface lie on the same plane, called the plane of incidence
Refraction
The travel of light from one medium into another where it has a different speed
Snell’s law
n1sin(theta1) = n2sin(theta2)
Refractive index formula
nm = c/cm
c = speed of light in a vacuum
cm = the speed of light in the medium
Dispersion
Rays that are refracted by different angles due to differences in wavelength
Critical angle
The angle of incidence for which the angle of refraction is 90
Total internal reflection
When the angle of incidence is greater than the critical angle so there is only a reflected ray
Diffraction
The spreading of a wave as it goes past an obstacle or through an aperture
When does diffraction take place?
When a wave with a wavelength comparable to or larger than the size of an aperture or an obstacle moves through or past the aperture or obstacle
The larger the wavelength, the __ the effect of diffraction
Greater
Path difference
The distance of the point from the two sources
Constructive interference
When individual waves with the same wavelength, frequency and speed meet resulting in a wave with double the amplitude
Destructive interference
When individual waves with the same wavelength, frequency and speed meet and cancel each other out resulting in no amplitude
When does constructive interference occur?
When the path difference is n(wavelength) where n = 0, 1, 2, 3, …
When does destructive interference occur?
When the path difference is (n + 0.5)(wavelength) with n = 0, 1, 2, 3, …
