Chapter 12 - Light Flashcards
The angle of incidence is always between ______ and _______
The incidence ray and the normal
FIVE characteristics of image form on a plane mirror
Image same size as the object Virtually converted Upright Virtual Image distance from mirror same as the object distance from mirror
Use of mirror
Vision Testing
When refraction of light happens?
When light enter a medium from another medium with different density
When light enters a optically denser medium from a less dense medium, it will bend _______ the normal, WHY?
Towards the normal
This is because the speed of the light slow down when it enters a denser medium
When light enters a optically less dense medium from a denser medium, it will bend _____ away from the normal, WHY?
Away the normal
This is because the speed of the light increases
When angle of incidence is 0 degree, what is the angle of refraction?
0 degree, there is no refraction
In a situation of the light enters from air to glass to air again, the both angles of light in air must be PARALLEL , T/F
True
Laws of reflection (2)
The incident ray, reflected ray and the normal at the point of incidence all lie in the same plane
The angle of incidence is equal to the angle of reflection
Refractive Index =
sin (
Define Refractive Index
The ratio of the speed of light in vacuum to the speed of light in the medium
The greater the refractive index value, the ______ more the bending of light as it enters the medium from air
More
Laws of Refraction
The Incident Ray, Normal and the refracted Ray all lie in the same plane
For two given media, the ratio of the size of the angle of incidence, i, to the size of the angle of refraction, r, is a constant
Refractive Index (denser to less dense) =
sin (
Refractive Index (light from air to breaker) =
Real Depth / Apparent Depth
Define Critical Angle
Angle of incidence in an optically denser medium for which the angle of refraction in the optically less dense medium is 90 degree.
When do total internal reflection occurs?
When light enters a OPTICALLY less dense medium from a OPTICALLY denser and the angle of incidence is increased beyond the critical angle
Critical Angle (Angle of Incidence)
Refractive Index = Sin 90 (
Use of internal reflection
Pentaprism in camera which allow the photographer to see the actual picture
Another use of internal reflection - Optical Fibre, how does it work and what are the advantages
The optical fibres is made of pure glasses. The core is made of pure glass with high refractive index and the cladding is made of pure glass with low refractive index. Hence, the light inside a core are totally internally reflected.
Adv. Optical Fibre replaces copper wires in television system as it is THINNER, CHEAPER, CARRY MORE SIGNAL.
What a lens diagram consist of?
Lens, Centre of lens
Principle axis, horizontal line through the middle of lens
Focal Point
Focal Length, Distance between the centre of lens and the focal point
Three Special Ray for converging lens
An incident ray through the optical centre C passes without bending
An incident ray parallel to the principle axis is refracted to pass though F
An incident Ray pass through the Focal point F is refracted parallel to the principal axis
Details of Ray diagram when object is behind 2F
Image is between F and 2F Inverted Real Diminished Uses: Camera
Details of Ray Diagram when Object is at 2F
Image at 2F Inverted Real Same Size Uses: photocopier
