How does light make shadows?

How does light make shadows?

By Mike Cummings

​When light hits an object's surface, many photons bounce off and go in many different directions, this is called "scattering". These photons reflect off at random angles. This is why we can see an object from many different angles.

​When light hits an unsmooth surface light scatters in many different directions! We see objects because the scattered light enters our eyes.

Multiple Choice

Light that bounces off of an object at random

angles is said to be what type of light?

• bouncing light

• absorbed light

• scattered light

• shadowed light

​Sometimes when light hits an object, photons get absorbed. Photons that are absorbed, force the object to gain energy. Photons create particles of matter to gain Kinetic Energy, this energy creates friction which then creates Thermal Energy, or heat!

​When photons hit matter, particles of matter are forced to move. Darker objects absorb more light energy and get hotter. Lighter objects reflect more light energy and stay cooler.

Multiple Choice

Photons force particles of matter to move due to the momentum/force that photons have. The movement of particles is known as;

• Kinetic Energy

• Solar Energy

• Thermal Energy

• Light Energy

Multiple Choice

Lighter objects absorb more light energy

and tend to get hotter than darker objects.

• True

• False

​Some objects react to light by allowing most light through. These objects are called transparent. Window glass is an example of something that is transparent.

Multiple Choice

Objects that allow most light through are

said to be;

• Invisible

• Opaque

• Translucent

• Transparent

​Some objects allow some light through and block some light, often blurring the image as you look through are known to be translucent.

Multiple Choice

Objects that allow some light through while

blocking some light is said to be;

• Invisible

• Translucent

• Transparent

• Opaque

​Other objects that do not allow any light through are said to be opaque. Opaque objects block all light.

Multiple Choice

If no light is allowed to pass through

an object, it is said to be;

• Invisible

• Opaque

• Transparent

• Translucent

Multiple Choice

The blue cup on the left is;

• Invisible

• Translucent

• Transparent

• Opaque

Multiple Choice

The green cup in the picture on the left

would be considered;

• Opaque

• Translucent

• Invisible

• Transparent

​Translucent and opaque objects block some or all light from going through them. This creates darker areas behind them known as a shadow. A shadow is the absence of light.

​When an object is between a light source and another object like a wall, the first object will cast a shadow on that other object. The light can be natural like the Sun or artificial like a lamp.

​Shadows can appear long or short depending on the ANGLE of the light source. A high angle creates short shadows, a low angle the shadow is long. At noon, the Sun is high so your shadow will be short, while at sunrise or sunset the Sun is low so your shadow will be long!

Multiple Choice

The length of a shadow depends on;

• The amount of light

• The direction the light comes from

• The angle at which

  the light comes from

​The direction of light also affects where your shadow is located. The Sun lies south of us because it lies near the equator. So, at noon your shadow is pointing north! At sunrise when the sun rises in the east, your shadow points in the opposite direction, which is west!

Multiple Choice

In which direction would your shadow be going at sunset,

when the Sun goes down in the west?

• You have no

  shadow

• It will be pointing south

• It will be pointing west

• It will be pointing east

​Closeness of the light source also affects the appearance of light! The closer the light source the larger the shadow, the farther the light source is away, the smaller the shadow will be!

Multiple Choice

What occurs to your shadow as you get

closer to a light source?

• It will get bigger

• It will get smaller

• Direction of a light source

• Closeness of a light source

• Angle of a light source

​So, there are three things that affect the appearance of your shadow, they are:

​Did you know you can have more than one shadow? Remember light rays can pass through each other without interference. So, the number of shadows you have depends on the number of light sources there are interacting with you.

Multiple Choice

If there were 5 different light sources placed in different places would;

• create only

  one shadow

• create only

  three shadows

• no shadows

  would be created

• create only

  five shadows

​Light affects shadows in four ways! The intensity or brightness of light, the direction of light, the angle of light and the number of lights.

Multiple Choice

Which of the following things about

a light source does NOT affect a shadow?

• The intensity/

  brightness

• The angle of

  the light

• The direction of

  the light

• What the object

  is made of

• The number of

  lights

​Light is amazing!!