Lecture 3 - reflection Flashcards
What is the law of reflection
The incident ray, reflected ray and the normal, at the point of incidence all lie in the same place
Rule of reflection
Angle of incidence is EQUAL to the angle of reflection
Are plane mirror images real or virtual
Virtual
What is a virtual image
They cannot be projected onto a screen - image appears behind mirror - cannot touch it
How can an image be located
By taking two image rays ( after reflection ) and extrapolating backwards - where they converge = point of image
How is virtual image formed
Light rays ( enter eye ) around room bounce off object, rays entering eye, extend them backwards - image behind eye - virtual - cannot touch it
Is the image inverted for plane mirror images
Yes ( laterally - left to right reversal )
Is image same as object for plane mirror images
Yes
What happens during mirror rotation
Light ray hitting mirror is perpendicular to it - light ray reflects straight backwards
Send light at different angles
Concave mirrors
positive
converging
what is centre of curvature
centre of mirror that the mirror forms part
radius of curvature
distance from surface to centre to curvature
focal length
half radius of curvature for a mirror
equation for focal length and radius
f = r/2
focal point
point on optical axis where rays meet if the rays before refraction are parallel to each other and optical axis
