Flashcards in ⭐️Topic SP5 - light and the EM spectrum Deck (82)
How can you model wether light is reflected or refracted?
-a ray diagram
-using waves on water
What is the normal?
The line on a ray diagram at right angles to the barrier/mirror
From where do you measure the angles of the incident ray and reflected ray?
From the normal
What is the law of reflection?
Where the angle of reflection is equal to the angle of incidence when waves are reflected
What is refraction?
Where light changes speed upon moving into a different material
When doesn’t light change direction when meeting a different density?
When it enters the material along the normal at right angles to the boundary
What happens to the reflection of light when it travels from water/glass to air with small angles of incidence?
Most of the light passes through the interface and little is reflected
What is total internal reflection?
When the angle of incidence is greater than the critical angle and the light is completely reflected inside the block
When does refracted light pass along the interface of the glass block?
When angle of incidence = angle of refraction.
What are non luminous objects?
Objects that do not reflect light
What is diffuse reflection?
Reflection from objects with a rough surface that cause the light to scatter in all directions.
Give an example of specular reflection
A mirror as light reflects evenly
What colours make up white light?
Red, orange, yellow, green, blue, indigo, violet
What does a prism do to light?
Split it up into a visible spectrum
Why does an object look a specific colour?
Because it absorbs all the colours of the spectrum but reflects the colour it looks
Why do object look white?
As it absorbs all colours
How can light be made coloured?
By transmitting the colour they look and absorbing the rest?
What colours in white light are transmitted and absorbed by red glass?
Red light is transmitted and all the other colours are absorbed
What does the power of a lens describe?
How much it bends light that passes through it
The more powerful a lens...
The more curved it is and the more it bends light
Describe a converging lens
It’s fatter in the middle than at the edges and makes parallel rays of light converge at the focal point
What is the focal length?
Distance between the focal point and the centre of the lens
Describe a diverging lens?
It’s thinner in the middle than at the edges and the rays seem to be coming from the focal point after passing through the lens
What is a real image?
An image that can be projected on a screen
What is needed to form a real image?
A converging lens as it can only be formed by rays that come together
What kind of image do you get you put an object near a converging lens?
A virtual image that looks bigger than the actual object and appears in front of the object
What kind of image do you get when you put an object far from a converging lens?
A real image that appears behind the lens, smaller than the object as upside down
What is a virtual image?
An image that can’t be projected onto a screen
What kind of image do diverging lenses always produce?
Virtual images that are the same way up and much smaller and closer to the lens that the object