# Physics Form 4

Topics: Geometrical optics, Optics, Refraction Pages: 2 (442 words) Published: September 6, 2011
FORM 4 – CHAPTER 5
LAW OF REFLECTION
Incident ray , reflected ray and normal line all lie in the same plane Angle of incident = angle of reflection
Real image is a image that can be seen on a screen
Virtual image is a image that cannot be seen on a screen
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Centre of curvature ( C ) – centre of sphere of the mirror Principle axis – the connecting line from the centre of curvature to point P Radius of curvature – the distance between the centre of curvature and the surface of the mirror Focal point

1 concave mirror – Is the point of the principle axis where all the reflected rays meet and converge 2 convex mirror – Is the point on the principle axis where all the reflected rays appear to diverge behind the mirror Focal length - Distance between focal point and surface of mirror Object distance ( u ) – distance between object and surface of mirror Image distance ( v ) – distance between image and surface of mirror ========================================================================== LAW OF REFRACTION

Light travel from one medium to another medium which has a different optical density Angle of incident , angle of refraction at point incident all lie in the same plane Snell’s law states that the ratio of sin of the angle incident ( sin i ) to the ratio sin of the angle refraction ( sin r ) is a constant n = speed of light in vacuum ( 3 x 10* )

speed of light in medium
Refractive index has no units
Bend away – speed increase
Bend forward – speed decrease
Higher refractive index = greater bending effect on light ( slows the light more ) Refractive index = real depth / apparent deph
Total internal reflection
N = 1 / sin c c : critical angle
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LENS
Concave lens ( characteristics same )
# focal point / principle focus
-A point on the principle axis to which incidents rays of light travelling...