WHAT IS LIGHT SO WHAT EXACTLY IS LIGHT

WHAT IS LIGHT?

SO WHAT EXACTLY IS LIGHT? BEFORE WE GO ON ANSWER THESE QUESTIONS: Can you see all light? What do different color lights mean? How big is light? How fast can light move across a room? How fast is that compared to the fastest runner? What about compared to a rocket? What is light made of? Is it on the periodic table? Can you catch or hold light? If so, how? If not does it interact with what it touches?

WHAT IS LIGHT? CAN YOU SEE ALL LIGHT? People can only see light in the visible light range. Goldfish are the only animal known to see in UV and IR range. Butterflies have the widest range of vision and can see UV light. Reindeer also can see UV light Some snakes and fish can see IR light.

WHAT IS LIGHT? WHAT DOES THE COLOR OF LIGHT MEAN? The color of light is determined by the wavelength of light. Just like waves on the beach, there is a distance between the top of one peak and the top of the next. This distance varies and the color we see depends on the length between those waves (wavelength). The wavelength tells us the about energy of the light.

WHAT IS LIGHT? SO WAVELENGTH IS THE DISTANCE BETWEEN TWO TOPS OF THE WAVE. BUT WHAT IS THE WAVE MADE OF? Light is made up of photons. Photons are not elements so they are not found on the periodic table. Photons have zero mass – they weigh nothing.

SO WHAT EXACTLY IS LIGHT? SO FAR, WE KNOW: NO Can you see all light? Wavelength What do different color lights mean? Photons. No. What is light made of? Is it on the periodic table?

SO WHAT EXACTLY IS LIGHT? HOW BIG IS LIGHT? IN OTHER WORDS, HOW BIG ARE PHOTONS? 1. 3 x 10 -4 m 2. 5 x 10 -15 m 0. 5 m 1. 35 x 10 -14 m 1 x 10 -18 m Electron Hydroge n Gold Marble Car Tire Where would photons fall on this list? Remember that they have no weight. Somewhere much smaller than an electron. So small that we call it a point and assign it no size.

WHAT IS LIGHT? Photons move at the speed of light which is 1080000000 km/h A photon has no mass and essentially no size, but its there. 670459516 mi/h Considering this how fast can it move if nothing was in its way? Fastest sloth: 0. 24 km/h 0. 15 mph The fastest person: 45 km/h 28 mph The fastest bullet 29, 000 km/h 18, 000 mph The fastest spacecraft (NASA’s Juno probe): 266, 000 km/h 165, 000 mph

WHAT IS LIGHT? CAN YOU CATCH OR HOLD LIGHT? Since a photon has no weight or size what about it could you catch? You couldn’t catch or hold photons in your hands, but you Can catch the energy they have. This is the idea behind solar panels.

SO WHAT EXACTLY IS LIGHT? TODAY WE ALSO LEARNED: So small it does not really have a size How big is light? Travels at the speed of light. Way faster than our fastest rocket. How fast can light move across a room? How fast is that compared to the fastest runner? What about compared to a rocket? You can not hold a photon But you can capture its energy with a solar panel Can you catch or hold light? If so, how? If not does it interact with what it touches?

MORE QUESTIONS ABOUT LIGHT Spend ten minutes writing your own questions about light that were not answered. Here are some examples: If the sun light is not captured by a solar panel, what would it do? If wavelength gives light its color what gives it brightness/intensity? How do lightbulbs make photons? What about candles? Is it the same way?