HEAT & LIGHT EXPLANATION
Questions we're going to answer:
Question: Are light and heat the same thing?
Answer: NO!!!!!!
Vocabulary:
Heat:
- Are light and heat the same thing?
- Can you have one w/o the other?
- How are heat and light related?
- What is light then and how do they relate to matter?
- What is heat then, and how does it relate to matter?
- What are some ways to generate heat?
- Can I convert light to heat and heat to light?
- Can I make light w/o heat?
- How does light & heat relate to the meteorite, car crashing and ball labs?
Question: Are light and heat the same thing?
Answer: NO!!!!!!
Vocabulary:
Heat:
- The vibrations & motions of atoms or molecules that make them move and collide into each other.
- It is the kinetic energy of the moving atom.
- It's what makes the difference between a substance that is capable of being a solid, liquid or gas - such as water.
Light:
- The emission of electromagnetic radiation due to the motion of charged particles.
Electro-
Refers to the electric fields generated by the charged particle. |
Magnetic
Refers to the magnetic fields that are induced by a moving charged particle. |
Radiation
Means that it's "going out" from the source - which is referring to the moving charged particle. |
Computer Model: Phet "Radiating Charge"
Note: This shows electrical field from a positive charge - but it does not show magnetic fields.
This model is about electric fields - which is a precursor in the field of physics to understanding what light is/was.
This is before Maxwell figured out that electric fields and magnetic fields were connected.
Note: This shows electrical field from a positive charge - but it does not show magnetic fields.
This model is about electric fields - which is a precursor in the field of physics to understanding what light is/was.
This is before Maxwell figured out that electric fields and magnetic fields were connected.
Speed of Light (C) = wavelength x frequency
300,000,000 m/s
Because the speed is the same, there is a reciprocal relationship with the frequency and wave length.
Physicists also found that there is a relationship with frequency and energy.
Speed = wavelength x frequency
Assuming the speed stays constant (which it does), this means that as you increase the wave frequency, the wavelength decreases, and visa versa.
Since the speed of light (C) is also always the same [which = 300,000,000 m/s], there is also a relationship between frequency and wavelength, which is noted in the table below.
It's this relationship that gives rise to the spectrum of light, which ranges from radio waves to gamma waves.
300,000,000 m/s
Because the speed is the same, there is a reciprocal relationship with the frequency and wave length.
- If you have a high frequency, you get a short wave.
- If you have a low frequency, you get a long wave.
Physicists also found that there is a relationship with frequency and energy.
- The higher the frequency, the more energy.
- The lower the frequency, the less energy.
Speed = wavelength x frequency
Assuming the speed stays constant (which it does), this means that as you increase the wave frequency, the wavelength decreases, and visa versa.
Since the speed of light (C) is also always the same [which = 300,000,000 m/s], there is also a relationship between frequency and wavelength, which is noted in the table below.
It's this relationship that gives rise to the spectrum of light, which ranges from radio waves to gamma waves.
Physicists later figured out how to calculate the energy associated with light. Max Plank was one such physicist. He figured out that the energy of light is very closely associated with its frequency.
E = hf
What this means is that when the frequency is increased, the energy is also increased. This also means that radio waves have a significantly low amount of energy - while gamma radiation has a large amount of energy.
This video introduces you to the electromagnetic spectrum.
So what does this mean about red and violet? What are some key differences between the two of them?
Well... if you'll notice, the main differences are the lengths of the waves - which means that the frequencies are also different.
What this also means is that red has less energy than violet.
Well... if you'll notice, the main differences are the lengths of the waves - which means that the frequencies are also different.
What this also means is that red has less energy than violet.
Since the visible light is a small part of the spectrum, and red is the lower level of energy when compared to violet, you may also notice two other adjacent forms of light that are next to red and violet; namely, infra-red and ultra-violet.
Infra means below, and Ultra means above. This is in reference to the level of energy.
This means, that ultra-violet has more energy than violet, and infra-red has less energy than red.
Infra means below, and Ultra means above. This is in reference to the level of energy.
This means, that ultra-violet has more energy than violet, and infra-red has less energy than red.
SOLAR SPACE HEATER
This is why when a solar space heater turns on, it does not immediately turn red - but rather eventually glows red as the metal filament gets hotter.
What it's doing is as the energy levels of the hot atoms increase, the filament glows in the infra-red region, and then eventually begins to glow red/orange.
What this means is that hot things emit light.
What it's doing is as the energy levels of the hot atoms increase, the filament glows in the infra-red region, and then eventually begins to glow red/orange.
What this means is that hot things emit light.
WHY WE FEEL HEAT FROM THE SOLAR SPACE HEATER
Why we feel heat is due to one of three modes of heat transfer called radiation. As an atom gets hot, it vibrates. The charged particles create electromagnetic disturbances that radiate out from the source. Hmm. That sounds familiar doesn't it? Yup. Light.
This light affects the atoms in the skin which also begin to oscillate - which makes the person feel warm.
This light affects the atoms in the skin which also begin to oscillate - which makes the person feel warm.
HEAT WILL PRODUCE LIGHT
Phet Program on Blackbody Radiation
What am I trying to say? Any time you have an object that has heat will also emit light. However, not all light is due to heat.
THERMAL CAMERA PICKS UP INFRA-RED
Points from the video:
- There is no such thing as cold energy, rather less heat.
- Heat travels from hot materials to cold materials. It's natures way of trying to balance things out.
- Heat travels in one of three different ways:
- Conduction
- This is when heat transfers when two materials touch each other -
- like you touching a hot pan and feel the heat enter your hand (feels hot)
- or you touching ice-cubes, and feel the heat leave your hands (feels cold)
- This is when heat transfers when two materials touch each other -
- Convection
- This is when heat transfers within a moving fluid.
- This is why most people say "heat rises", which is slightly wrong - it's "hot fluids rise".
- A fluid is any material that flows within its self - such as a gas or liquid.
- This is when heat transfers within a moving fluid.
- Radiation
- This is heat transfer through light. This is what we've been studying the entire time and you didn't even know it. Most of the heat you feel from a hot body emits infra-red light - aka, radiation.
- That warm feeling you get when you stand next to a fire, or in the hot sun is due to radiation.
- This is heat transfer through light. This is what we've been studying the entire time and you didn't even know it. Most of the heat you feel from a hot body emits infra-red light - aka, radiation.
- Conduction
DIFFERENT WAYS TO MAKE LIGHT
There are many ways to make light. Only one of these processes involves excessive amounts of heat (incandescence). This mode of making light is highly in-efficient, because most of the energy is in the form of heat and not so much as light. This is why we have been making the move to more energy efficient ways to create light - like the processes that make LED and CFL lights work.
Below are just a few ways to make light.
Source: https://emmybella.wordpress.com/production-of-light/
Below are just a few ways to make light.
- Incandescence (uses heat)
- Electric Discharge
- Phosphorescence
- Fluorescence
- Chemiluminescence
- Bioluminescence
- Triboluminescence
Source: https://emmybella.wordpress.com/production-of-light/
SUMMARY
What am I trying to say?
- What I'm trying to say is that when you have heat, you will always have light.
- But, not all light is generated by heat.
- Therefore, heat and light are not the same thing - but they do have a relationship.
- That relationship is called black body radiation.
- As you increase the level of energy - you also increase the frequency of light
SOURCES
General info about light: https://www.education.com/reference/article/what-how-light-produced/
Different ways to produce light: https://en.wikipedia.org/wiki/List_of_light_sources
https://quizlet.com/23169944/6-ways-to-produce-light-flash-cards/
https://emmybella.wordpress.com/production-of-light/
Different ways to produce light: https://en.wikipedia.org/wiki/List_of_light_sources
https://quizlet.com/23169944/6-ways-to-produce-light-flash-cards/
https://emmybella.wordpress.com/production-of-light/