Q3 Flashcards
Give one difference between a real image and virtual image?
A real image is formed by the actual intersection of light rays and can be formed on a screen (inverted image). A virtual image is formed by the apparent intersection of light rays and cannot be formed on a screen (upright image).
What is meant by the reflection of light?
Bouncing of light.
When does reflection not occur as a ray of light travels from one medium to another?
When light strikes a boundary between two media at a right angle.
What is refraction of light?
The bending of light as it passes from one medium to another.
State the laws of refraction of light?
The incident ray, the refracted ray, and the normal all lie in the same plane.
State Snell’s law of refraction?
The sine of the angle of incidence is proportional to the sine of the angle of refraction, sin i / sin r, and is equal to the refractive index (n).
Define Refractive Index?
Refractive index = speed in less dense medium / speed in more dense medium = sin i / sin r.
When does a ray of light not change direction when it passes from one medium into another?
When the two media have the same optical density or refractive index, or when the ray strikes the boundary at right angles.
Explain the term total internal reflection?
TIR occurs when the angle of incidence in the more dense medium exceeds the critical angle. It is used in optical fibers, reflectors on bike pedals, reflective clothing, and rear lights.
What is the Critical Angle?
The angle of incidence corresponding to an angle of refraction of 90°.
How can the refractive index be calculated using a graph?
A sin i vs. sin r graph can be used to get the refractive index by calculating the slope, which is directly proportional.
Name the phenomenon that occurs when a ray of light strikes the glass/air boundary at an angle of incidence of 40°?
Total Internal Reflection.
What is the relationship between focal length (f) and the radius of curvature (c) of a spherical mirror?
The focal length is half the radius of curvature, so c = 2f.
Give two properties of the virtual images formed in a convex mirror?
Diminished, laterally inverted, and located behind the mirror.
Give one advantage and one disadvantage of using a convex mirror instead of a plane mirror as the exterior door mirror on a car?
Advantage: Wide field of view, always upright. Disadvantage: Image is diminished, and image distance is reduced compared to the actual distance.
Explain monochromatic light?
Monochromatic light consists of one frequency or wavelength of color.
State one property of a wave that changes?
Speed (when passing through different media), direction, wavelength.
State one property of a wave that does not change when it is refracted?
Color or energy remains the same; it stays in the same location on the electromagnetic spectrum.
How could you detect the presence of the invisible spectrum?
Using a thermometer.
Where would you expect to detect infrared radiation?
Beyond the red end of the visible spectrum.
Give one application of optical fibers?
One application of optical fibers is in medical endoscopes.
Why does refraction not occur as a ray emerges from Perspex?
Refraction does not occur when the ray strikes the boundary between the two media at right angles.
Define diffraction?
Diffraction is the spreading out of waves as they pass through a narrow gap or when they encounter an obstacle.
Define interference?
Interference occurs when two or more waves superimpose (meet).
How does light show a wave nature?
Light has a wave nature, as shown by diffraction and radiation.
What is a photon?
A photon is a unit of light energy.
Define the photoelectric effect?
The photoelectric effect is the release of electrons from the surface of a metal when irradiated with light of a certain frequency or UV light.
Define frequency?
Frequency is the number of waves per second.
Formula for speed of a wave?
Speed of a wave (c) = frequency (f) x wavelength (λ).
Properties of infrared radiation?
Infrared radiation has a heating effect, a frequency less than visible light, and lower energy than visible light and UV light.
Define constructive interference?
Constructive interference occurs when waves meet in phase.
Define destructive interference?
Destructive interference occurs when waves meet out of phase.
Define wavelength?
Wavelength is the distance from crest to crest of a wave.
