π¦ β’ Lesson 3.4 : Waves and Light (Phys) Flashcards
This deck will contain all about the general properties of waves, the reflection and refraction of light, dispersion of light and converging lens.
How do waves transfer energy?
Waves transfer energy without transferring matter, meaning the energy moves through the medium, but the particles of the medium stay in place.
What is wave motion?
The transfer of energy through vibration or oscillation, (such as in ropes, springs, or water waves).
What is a transverse wave?
In a transverse waveβ¦
The vibration is at right angles to the direction of wave travel.
Examples: electromagnetic radiation, water waves, and seismic S-waves.
What is a longitudinal wave?
In a longitudinal waveβ¦
The vibration is parallel to the direction of wave propagation.
Examples: sound waves and seismic P-waves.
What are the features of a wave?
Wavelength, frequency, crest (peak), trough, amplitude, and wave speed.
What happens when waves reflect?
Waves bounce off a plane surface.
What happens when waves refract?
Waves change direction when their speed changes in different mediums.
How do waves diffract?
Waves diffract when they pass through a narrow gap, spreading out in the process.
What is the equation for wave speed?
v = fΞ»
(wave speed = frequency Γ wavelength).
How does wavelength and gap size affect diffraction?
Waves diffract more when the gap size is close to the wavelength.
Larger gaps cause less diffraction.
What are the terms normal, angle of incidence, and angle of reflection in ray diagrams?
β’ Normal: A line perpendicular to the surface at the point of incidence.
β’ Angle of incidence: The angle between the incident ray and the normal.
β’ Angle of reflection: The angle between the reflected ray and the normal.
How is an image formed by a vertical plane mirror?
The image formed by a vertical plane mirror is the same size as the object, at the same distance from the mirror, and laterally inverted (flipped horizontally).
Why is an image formed by a plane mirror virtual?
The image is virtual because the light rays donβt actually converge but appear to come from a point behind the mirror.
What is the relationship between the angle of incidence and angle of reflection?
The angle of incidence is always equal to the angle of reflection (i = r).
What is refraction?
Refraction is the change in direction of a light ray as it passes from one medium to another.
What is the refractive index?
The ratio of the speed of light in one medium to the speed of light in another medium:
n = sin(i) / sin(r).
What happens when light passes through a transparent material?
It bends (refracts) at the boundary between the two media, with the amount of bending determined by the refractive index.
What is total internal reflection?
Itβs when light is completely reflected back into a medium because it hits the boundary at an angle greater than the critical angle.
What is the critical angle?
The angle of incidence where the angle of refraction is 90Β°.
Beyond this, light reflects completely.
How does total internal reflection occur in optical fibres?
Light reflects within the fibre, staying inside it and allowing long-distance transmission,
(Ex. used in telecoms and medical devices).
How does a thin converging lens act on a parallel beam of light?
It focuses parallel rays of light to a point called the focal point.
What are the principal axis, principal focus, and focal length?
β’ Principal axis: The central line through the lens.
β’ Principal focus: The point where light rays converge.
β’ Focal length: The distance from the lens to the focal point.
How does a converging lens form a real image?
Light converges at a point, forming an inverted image on the opposite side of the lens.
How does a converging lens form a virtual image?
Light rays appear to come from a point on the same side as the object, forming an upright, magnified image.
How are the characteristics of an image described?
The size (enlarged, same, or reduced), Orientation (upright or inverted), type (real or virtual).
How does a single lens function as a magnifying glass?
It forms a virtual, upright, and magnified image when the object is close to the lens.
What is the dispersion of light?
White light splits into a spectrum of colors when refracted through a prism.
