How does light travel?

Answer 1

Great question! Light actually moves in waves. How big those waves are determines what type and color of light it is. Those waves, however, are so small that they appear to be straight lines.

The complicated part is that light moves in straight lines only when it’s not moving through anything at all (ie. in a vacuum). When it moves through air, water, glass, or anything else, its behavior changes. There are two main things that happen to change the direction of the light’s motion:

(1) Reflection. Reflection is what happens when light bounces off of something. This is what you see when you look in the mirror. This is also what you see when you look at anything around you. In order to reach your eyes, light bounces off of the object that you’re looking at, changing its direction. It can also bounce off of particles (like water) in the air, which is why you may be able to see beams of sunlight on a foggy day.

(2) Refraction. Refraction is what happens when light passes from one medium (one type of stuff) into another. When this happens, the light will actually bend. (Actually, it usually splits in two - some of it reflects off the surface, and some of it keeps going through.) The light that goes through bends at the surface. The angle that it bends at depends on what the two mediums are. For example, light will bend a different amount when it goes from air into glass than it does when it goes from air into water.

Answer 2

There were some important disoveries that led to our understanding of how light travels (propogates). Likely, the biggest discovery was the understaning that light and electromagnetic radation are the same thing.

James Maxwell discovered that light was a form of electromagnetic radiation. It consists of two forces, a changing electric field and a changing magnetic field.

Scientists in the 1800's discovered that a changing magnetic field produces a changing magnetic field and a changing electric field produces a changing magnetic field. You can get a feel for this from an electromagnet. Notice how a mangetic field is produced when an electric current passes through a wire wrapped around a nail. But the magnetic field is static and the field is local and doesn't propagate. Direct, steady state electric current doesn't propagate a wave. Now alternate the current so that it flows in one direction and then revereses in the other direction. Alternate the electric current at high frequencies such as done when broadcasting a radio signal. You will produce an electromagnetic wave at a frequency of the changing electric current.

The idea is that the quickly changing electric field in the wire is creating a similar changing magnetic field but with some delay. When the magnetic field changes, it creates a second electric field that propagates away from the magnetic field. So the two changing forces tend to "push" each other further and further until the energy diminishes. What we pickup with our radio receiver is this wave as some distance from the source. If the radiation is within a certain band of frequencies, we see it as light.

Answer 3

Light travels in a straight line.

Answer 4

How Does Light Travel?

Grade: 4

Time: 20 minutes

Materials: For each group, three 3x5 cards with hole [hole punch]
punched through each; the holes should be the same distance up from the
bottom but randomly between the edges. One thin straw, flashlight, a
card WITHOUT a hole. Light bulb in holder for class demonstration,
radiometer toy.

Concept:
In air or other transparent medium light travels in a straight line from
source to object.

Objective:
Students will line up cards so that light can pass through all three
holes onto the card used as a screen. Students will verify that the path
is a straight line by inserting the straw through the holes that are
lined up.

Set:
Did you ever wonder about seeing around a corner. Today we are going to
see why you can't see around a corner. First I want you to do a little
predicting for me. I have up here a light bulb [turn on]. Draw me a
picture of your best idea right now for how you are able to see the lamp.
[Alternate Set - (Use caution. Careless use may cause the straw to touch
the cornea and the scratch is VERY painful) Carefully hold a straw up to
your eye and look through the straw. Close one eye if you need. Can you
see anything through the straw? Now bend the straw in the middle. Can
you still see anything? Today we are going to find out how light travels
as it comes to us.]

Instruction:
Notice what happens [darken room first] when I hold this toy up close to
the bulb [it spins]. As I move the toy away what happens [the spinning
slows down]. Something is coming from the light bulb that makes the toy
spin; it's called ........ LIGHT! The light moves away from the light
bulb and comes to the toy. The light comes from all sides of the bulb
[try it] and in all directions. But what is the path?

Put your flashlight on the table and shine the beam of light toward one
of the holes in a 3x5 card. On the other side of the card hold your
plain card screen. What do you see? [ans: a spot of light] Put a second
card with a hole in it BETWEEN the first card and your screen. Can you
get a spot of light still on the screen? [ans: may have to move the cards
around but there is a way when the spot of light from the FIRST card
falls on the hole in the second card] Does anyone need some
encouragement? [let another group assist] Now I want you to put a THIRD
card with a hole in it between the flashlight and the screen. Can you
STILL get a spot of light on the screen? [ans: there is an alignment.
Now I want you to lay down your screen and WITHOUT MOVING the other three
cards stick the straw into the holes. Can you get the straw through all
three holes without bending it?

Closure:
You have lined up three cards with holes so that the light can get
through. What kind of path do you think the light followed from the
flashlight to the screen? [ans: a straight line]. Now go back and look
at your picture that you drew. Do you need to change anything about it.
If you do, draw the new picture under the first one.

Assessment:
Look at the student drawings. They may not show light coming from the
lamp, or moving in straight lines or coming off all parts of the lamp or
going in all directions from EACH point of the lamp. Adjust further
discussion according to incomplete pictures.

Extension:
How can a mirror be arranged to enable one to see around a corner. Does
the light bend?

Adapted by Paul Lee
for SCI 442, MTSU, Summer 1996

Answer 5

Light travels in space as in air by c=3*10^8 it is a transverse waves depends on magnetic and electric fields that perpendicular to each other it propagates in the direction of propagation of the wave and it is an electromagnetic waves it has all the wave nature from reflection, refraction, diffraction and interfere it reflect when it passes from one medium to another and refract when it meet a reflector and diffract when it pass by narrow or sharp edges and interfere when two light waves are super positioned.

Answer 6

You counsel replaced into incorrect approximately all capability having mass. Radiation, or easy waves comprise no mass. some people argue that it has an 'effective mass' given via lots of the E=hf (engery=plank's consistent circumstances the frequency), yet that continues to be debated. Reguardless, easy has no mass, and that's the reason it may commute @ the cost of sunshine c. you're suited approximately accelerating a partlice in the direction of the cost of sunshine could require limitless quantity of capability. once you're somewhat intrested look @ Lorentz adjustments, and you would be able to work out the particularly uncomplicated why something with mass can no longer attain the cost of sunshine.

Answer 7

I've spoken with Light.
Light prefers to travel light.
Light carries nothing that can't be stuffed in an overhead bin.
And he prefers to travel MUCH MUCH faster than YOU!

Answer 8

It rides the light train.

Answer 9

As a light and a wave. just the same as radio or microwaves.

Answer 10

Usually in a straight line at 186,000 miles per second.