Wave behaviour Flashcards
What is the difference between a real image and a virtual image?
A real image is where the light from an object comes together to form an image on a screen
A virtual image is when the rays are diverging so the object appears to be coming from a completely different place (eg looking in a mirror or binoculars)
What 3 things do you need to say to describe an image properly?
How big it is compared to other objects
Whether it’s upright or inverted
Whether it’s real or virtual
What is the difference between a diffuse and clear reflection?
A clear reflection is off a smooth surface anjd the light rays reflect perfectly
A diffuse reflection is when light rays are reflected in all different angles due to a bumpy surface
Angle of incidence equals what?
Angle of reflection
What is refraction?
When light rays change direction when they hit a different material
What is a converging (convex) lens and a diverging (concave) lens?
A convex lens focuses light in
A diverging lens spreads it out
How to draw a ray diagram for a converging lens?
Plot F and 2F
Follow the top of the object to the lens and make it go through F
Have another line on the top of the object go through the centre of the graph
Where the lines meet will be the top of the image
What will happen if the object in a ray diagram is:
Beyond 2F At 2F Between 2F and F At F Between F and the lens
Smaller than the object
Same size as object
Larger than the object
Since the rays are parallel they will never meet so are formed at infinity
The image will be a virtual image larger than the object
How to draw a ray diagram for a diverging lens?
Draw a line going from the top of the object straight to the lens and a line going from the top of the object straight through the axis (The middle of the lens)
Carry on the line that’s refracted by the lens by carrying it on from F on the side of the object, drawing a dotted line (Making it carry on upwards, away from the axis)
Where the lines cross will be the image (in front of the lens)
What is the difference between real and virtual images?
Real images is where the light rays actually meet at that spot
Virtual is when the image is behind the glass (Eg. a mirror)
What is constructive and destructive interference between waves?
Constructive waves go in the same way as each other, so add to each other
Destructive cancel each other out as they go in separate directions
What is the human hearing frequency?
20 - 20,000 Hz
what is frequency?
The number of waves per second
