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 ____________________________________________________________ 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 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 ____________________________________________________________ __ LENS Concave lens ( characteristics same ) # focal point / principle focus -A point on the principle axis to which incidents rays of light travelling parallel to the axis appear to diverge after refraction through concave lens # focal length -Distance between the focal point , F , and the optical centre , C , on the lens Convex lens # focal point / principle focus A point on the principle axis to which incident rays of light travelling parallel to the axis converge after refraction through a convex lens # focal length -distance between the focal point , F , and optical centre POWER OF LENS = 1 / f f: is a metre and unit of power is m-1 / diopter ( D ) Power of lens = 10 D if focal length 0. 10m = 10cm 1 . power convex lens = +ve 2 . power concave lens = -ve Linear magnification , m = v / u = h (image ) / h ( object ) 3 . lens equation , ( 1 / u ) + ( 1 / v ) = ( 1 / f ) •v ( +ve ) = real image •v ( -ve ) = virtual image •f & p ( -ve ) = concave lens •f & p ( +ve ) = convex lens

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 ____________________________________________________________ __ LENS Concave lens ( characteristics same ) # focal point / principle focus -A point on the principle axis to which incidents rays of light travelling parallel to the axis appear to diverge after refraction through concave lens # focal length -Distance between the focal point , F , and the optical centre , C , on the lens Convex lens # focal point / principle focus A point on the principle axis to which incident rays of light travelling parallel to the axis converge after refraction through a convex lens # focal length -distance between the focal point , F , and optical centre POWER OF LENS = 1 / f f: is a metre and unit of power is m-1 / diopter ( D ) Power of lens = 10 D if focal length 0. 10m = 10cm 1 . power convex lens = +ve 2 . power concave lens = -ve Linear magnification , m = v / u = h (image ) / h ( object ) 3 . lens equation , ( 1 / u ) + ( 1 / v ) = ( 1 / f ) •v ( +ve ) = real image •v ( -ve ) = virtual image •f & p ( -ve ) = concave lens •f & p ( +ve ) = convex lens