Reflection, Refraction, Diffraction Flashcards
True or false: The critical angle is defined as an angle of incidence of 90 degrees.
This statement is false. The critical angle is the angle of incidence at which the angle of refraction is equal to 90 degrees, i.e. the angle of incidence at which total internal reflection occurs (remember that light cannot refract at an angle greater than 90 degrees).
When a wave encounters a barrier with a small opening some waves will hit the barrier and be reflected back, while other waves will pass through the opening and expand outward. This phenomenon is known as…
Diffraction occurs when light passes through a small opening in a barrier. The bending of light through the barrier causes the light to constructively and destructively interfere with itself in an observable pattern
Describe the differences between single and double slit diffraction
A double-slit diffraction produces a relatively even distribution of maxima and minima, with each minima occurring halfway between maxima. A single-slit diffraction, in contrast, produces a sizeable intensity peak in the center of the intensity graph flanked by alternating areas of weaker intensity peaks and darker regions
True or false: Light can undergo total internal reflection even if its angle of incidence is less than 45°.
This statement is true. Total internal reflection (TIR) is favored by a large angle of incidence. However, even if this angle is not enormously large, if the light is leaving a material with a sufficiently high index of refraction and entering a material with a sufficiently low one, it can experience TIR.
A light ray enters a diamond (n = 2.42) from the air (n = 1.00). What is the minimum angle of refraction that could logically be expected to occur and that would constitute total internal reflection?
This situation involves movement from a low-index material into a high-index one. Total internal reflection occurs when the opposite transition is made. Note also that this question asks for the “minimum angle of refraction,” not the “minimum angle of incidence,” or critical angle. If this situation were possible, the minimum angle of refraction would be 90°.
The differential refraction of different colors of light
dispersion
True or False: when traveling from one media to another, the wave can change in frequency
False, When light moves from a lower-index medium into a higher-index one, its velocity decreases. Mathematically, this change must be accompanied by a decrease in either frequency or wavelength; in reality, it is wavelength that decreases, while frequency remains unchanged.
Material A has a slightly higher index of refraction than Material B, which has a slightly higher index than Material C. If identical light rays were to enter each of these materials from a vacuum, which would bend the most significantly toward the normal?
A
True or false: If a medium has an index of refraction of 2.5, when light enters it from a vacuum, the wavelength of that light must increase by a factor of 2.5.
This statement is false. The higher the index of refraction, the slower light travels through the medium in question. For that reason, it would make sense for the wavelength to decrease (not increase) by a factor of 2.5.
True or False: EM waves all travel the same speed in a vaccum
True
True or False: EM waves do not travel the same speed in different media
true
All waves travel at the same speed through a vacuum, but the speed of propagation varies based on wavelength in all non-vacuum media. The speed of the wave is given by the equation v = fλ. When light enters into a glass prism from air, its wavelength will decrease, thus decreasing the wave’s velocity, resulting in dispersion. The smaller the wavelength, the greater the resulting decrease and bending.
