Hard Topics Flashcards
(29 cards)
What is the visible light spectrum?
A range of colours, each with its own narrow band of wavelength and frequency.
The visible light spectrum includes colours like red, orange, yellow, green, blue, indigo, and violet.
What is specular reflection?
Reflection from a smooth surface in a single direction.
Specular reflection is what allows us to see clear images in mirrors.
What is diffuse reflection?
Reflection from a rough surface that causes scattering.
Diffuse reflection results in a more uniform light distribution, making surfaces appear less shiny.
How do colour filters work?
By absorbing certain wavelengths (and colour) and transmitting other wavelengths (and colour).
Colour filters can change the appearance of light by selectively filtering out certain colours.
How is the colour of an opaque object determined?
By which wavelengths of light are more strongly reflected.
Wavelengths that are not reflected are absorbed, influencing the object’s perceived colour.
What happens if all wavelengths are reflected equally?
The object appears white.
White objects reflect all visible wavelengths of light.
What happens if all wavelengths are absorbed?
The object appears black.
Black objects absorb all visible wavelengths of light and reflect none.
What are the two types of objects that transmit light?
Transparent and translucent.
Transparent objects allow light to pass through clearly, while translucent objects scatter light.
What are the ways substances interact with electromagnetic waves?
Absorb, transmit, refract, reflect
These interactions can vary depending on the wavelength of the electromagnetic waves.
What phenomenon is caused by the difference in velocity of waves in different substances?
Refraction
Refraction occurs when waves pass from one medium to another and change speed.
What is Refraction?
Refraction is the change in direction of a wave when it passes from one medium to another, due to a change in wave speed.
Refraction occurs because waves change speed when they move between materials of different densities.
Why does refraction happen?
Waves change speed when they move between materials of different densities, causing the wave to change direction.
This phenomenon is a result of the relationship between wave speed and the density of the media.
What happens when a wave enters a more dense medium?
The wave slows down and bends towards the normal.
Example: Air to glass.
What happens when a wave enters a less dense medium?
The wave speeds up and bends away from the normal.
Example: Glass to air.
What remains constant during refraction?
The frequency stays the same; only speed and wavelength change.
This is crucial for understanding wave behavior across different media.
What is the normal in the context of refraction?
The normal is an imaginary line at 90° to the boundary.
It helps in measuring angles of incidence and refraction.
True or False: The angle of incidence is always equal to the angle of refraction.
False.
The angles are only equal when the wave enters at 90°.
What is Reflection?
Reflection is when a wave bounces off a surface.
It follows the rule: Angle of incidence = Angle of reflection.
What types of waves can undergo reflection?
Light, sound, water, etc.
Reflection occurs at boundaries between two different materials.
What is Transmission?
Transmission is when a wave passes through a material.
This often happens alongside refraction.
Give an example of transmission.
Light can be transmitted through glass or water.
What is Absorption?
Absorption is when the energy of the wave is taken in by the material.
The energy is usually converted into heat.
Which materials absorb light more effectively?
Black materials absorb light more than white ones.
Soft materials like foam absorb sound better.
What is Diffraction?
Diffraction is the spreading out of waves as they pass through a gap or around an obstacle.
It is most noticeable when the gap size is similar to the wavelength.
