21 John says,‘When hunting a fish under water, you should aim your spear directly at the fish.’Do you agree?Yes, of course.No, because the fish is actually located somewhere else.No, because size of objects changes when they are put under water.
32 When sunlight falls on the water surface, which of the following occur(s)? It is reflected back to the air.It refracts into the water.It is absorbed by water andturned into heat.
4Introduction Refraction is the bending of light when the light passes from one medium to another.airglass
5Introduction Useful words to describe refraction of light angle of incidenceincident raynormalairglassrefracted rayangle of refraction
6Introduction From a less dense to a denser medium e.g. from air to glassnormalincident rayairglassrefracted rayLight is bent towards the normal.
7Introduction From a denser to a less dense medium normal incident ray e.g. from water to airairwaternormalincident rayrefracted rayLight is bent away from the normal.
8Laws of refraction The incident ray, the refracted ray, and the normal all lie in the same plane.incident raynormalnormalairairglassglassrefracted rayrefracted ray
9Example 3 nw sin w= na sin a Applying Snell’s law, 1.33 sin w = 1 sin 30 sin w = sin 30/1.33= 0.376airwater30 w = 22.122.1
10Q1 A boy shines a torch under… A boy shines a torch under water as shown.Which one shows the correct path of the light ray?A Path X.B Path Y.C Path Z.D All of them.
11Q4 True or false: When light is… True or false: When light is incident on a surface along the normal, only refraction occurs; there is no reflection.(T/F)
121st statement 2nd statement Q5 Statements:...1st statement 2nd statementLight is bent towards the normal when it passes from air to glass.Glass has a greater refractive index than air.true?true?YesYes
134 Examples of refraction of light a Bent chopstickThe chopstick appears bent because of refraction
144 Examples of refraction of light b Shallower in waterOIreal depthThe depth that the object is actually at is called the real depth.Simulation
154 Examples of refraction of light c Flickering objects in hot airThe object you see through the unstable hot air appears blurred and flickering.
16Q1 True or false: Light slows… True or false: Light slows down when it enters a material from air.(T/F)
17Q2 True or false: The refractive… True or false: The refractive index cannot be smaller than 1.(T/F)
18Q3 True or false: If light travel… True or false: If light travel at the same speed in all materials, refraction would still occur when it passes from air to water.(T/F)
19Q4 True or false: If the speed of… True or false: If the speed of light in raindrop is equal to that in air, there would be no rainbows.(T/F)