explain reflection, bending
(refraction), and transmission of light.
Main Idea
When light hits a surface, the light can
be reflected, refracted, transmitted,
or absorbed.
Reflection
Light travels in straight lines called rays.
When light bounces off of an object or a surface, it reflects.
Light rays reflect from a surface according to the law of
reflection: they always reflect at the same angle that they
hit the surface.
Take a look at the mini-movie below. Click the
flashlight to turn it on. Watch what happens when the light ray from
the flashlight hits the surface of the mirror.
The ray from the flashlight hits the shiny
surface and reflects off it at the same angle. Your parents are able
to see behind them when they are driving their car because of the
law of reflection. They can see cars that are coming up behind because
the light reflecting off of the car hits their rearview mirror at
angle and then bounces to their eyes.
Rearview
mirrors work because of the law of reflection.
Refraction
When light rays enter a new medium at
angle, it refracts, or bends. This happens because the speed
that the light is traveling changes making the light change direction.
You probably have seen refraction take place when you've been swimming.
Objects on the bottom of the pool look different because light reflected
off them changes direction when it leaves the water and begins traveling
through air.
In science class you may have had the opportunity
to shine light through something called a refraction block. The block
is made of acrylic, which is similar to glass, and when light strikes
the surface of the block at angle, it bends. The mini-movie below
shows this in action.
Notice that as the light leaves
the refraction block, it bends again and travels at the same angle
it was going before entering the refraction block. We see refraction
in the real world all the time. Check out the examples below.
Refraction
in the Real World
Rainbows
are created when light shines through tiny drops of water. The
drops refract the light, separating it into colors.
Magnifying
lenses work when light is refracted as it passes through the
lens.
