Thermal Energy and Radiation

Conservation of Energy

• Energy is neither created nor destroyed, only transformed from one type to another
• Gravitational potential energy (GPE) is based on an object's height and calculated using the equation: GPE = mgh
• Kinetic energy is greater if an object moves faster and calculated using the equation: KE = 1/2mv^2

Power

• Power is the rate of work done over time, measured in units of horsepower (Hp), Watts (W), or joules per second (J/s)
• Mechanical power is the output of work done by a system over time, while electrical power is the amount of energy moved within a circuit over time
• Torque and angular velocity can be used to calculate mechanical power, while voltage and current can be used to calculate electrical power

Thermal Energy

• Thermal energy is the energy an object or system has due to the movement of its particles
• Thermal energy is both a type of kinetic energy and capable of doing work
• Thermal energy can be transferred through convection, conduction, and radiation

Radiant Energy

• Radiant energy is a type of energy that can transfer through empty space or a vacuum
• Radiant energy comes in the form of electromagnetic radiation and gravitational radiation
• All radiant energy travels at the speed of light, or approximately 300,000,000 meters per second in a vacuum
• Radiometry can be used to measure radiation flux in units of watts or joules per second

Chemical Energy

• Chemical energy is the energy stored in the bonds of chemical compounds
• Chemical energy is a form of potential energy
• Breaking atomic bonds requires energy, while forming new bonds releases energy
• Exothermic reactions involve substances that release more energy than they absorb, while endothermic reactions absorb more energy than they release

Nuclear Energy

• Nuclear energy is a form of energy released from the nucleus of atoms
• Nuclear energy is released through fission reactions when large atoms are split apart, or fusion reactions when small atoms are fused together
• Einstein's work on mass-energy equivalence helps explain how nuclear energy is possible

Heat and Temperature

• Heat is a form of energy that can be transferred from one body to another
• Heat causes thermal expansion of objects over the length, area, or volume dimensions
• The heat energy required to raise the temperature of a substance depends on the mass of the substance, the nature of the substance, and the temperature difference
• The heat capacity or thermal capacity of a body is the quantity of heat energy that results in a unit change in the temperature of the body

Energy and Living Organisms

• Energy is the ability to do work
• All living organisms require energy for survival and reproduction
• The sun provides energy for the entire planet, which is then transformed into more usable forms for living organisms
• Plants utilize photosynthesis to produce sugar and oxygen from carbon dioxide and water
• Cellular respiration is the synthesis of ATP using energy released by the breakdown of sugar to carbon dioxide and water

Waves

• A wave is a vibration or disturbance that travels from one point to another and carries energy
• Wave propagation refers to the movement of waves
• All waves have frequency, amplitude, wavelength, and wave speed
• Wave speed is determined using the equation: v = fλ
• Factors that affect wave speed include tension, rigidity, density, and temperature

Sound Waves

• Sound is a type of energy that vibrates and moves in waves
• Sound waves are longitudinal waves that require a medium in which to travel
• The amplitude of a sound wave is a reflection of how much energy is carried, which contributes to the intensity of the sound
• The frequency of a sound wave is perceived as pitch
• Humans can detect pitches within the acoustic range of 20 to 20,000 Hz

Electromagnetic Radiation

• Electromagnetic radiation is a wave that propagates through space, carrying energy at the speed of light
• Electromagnetic radiation includes seven types of light: radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays
• The electromagnetic spectrum is listed in order from lowest frequency to highest and from longest wavelength to shortest

Color

• Color is a form of electromagnetic radiation
• Human eyes are specialized organs that detect electromagnetic radiation
• The visible light spectrum is normally divided into seven pure spectral colors: red, orange, yellow, green, blue, indigo, and violet
• Each frequency corresponds to a particular color

Resonance

• Resonance is an occurrence in physics where a specific frequency of vibration causes a nearby object to increase the amplitude at which it vibrates

• Resonant frequency is the frequency at which an object naturally vibrates

• Resonance occurs in RLC circuits, musical instruments, and light waves### Interaction of Light with Objects

• When a light wave's frequency matches the resonance frequency of an object, absorption occurs.

• If all frequencies of the light wave match the resonance frequency of the object, the light wave will be completely absorbed.

Classification of Objects

• Objects can be classified as opaque, transparent, or translucent based on how they interact with light.
• Opacity is the degree to which an object blocks light from passing through.

Absorption and Reflection

• Light waves are absorbed when their frequency matches the natural frequency of the object they hit.
• When the frequency of the light wave does not match the natural frequency of the object, it is reflected.
• There are two types of reflection: specular and diffuse.

Transmission

• When light waves pass completely through an object, it is called transmission.
• Energy from the light wave passes to nearby atoms until it exits the other side of the material.
• Snell's Law states that the speed of the light wave remains constant in this situation.

Refraction

• When light waves do not completely pass through an object, but bend as they enter it, it is called refraction.
• Refraction occurs if the light wave enters an object with a different density.
• The bending of light waves is called refraction, and the object is translucent.

Refraction and Snell's Law

• When a wave passes from one medium to another, it bends, and this is known as refraction.
• Snell's Law states that the ratio of the angles of incidence and refraction is equal to the inverse ratio of the indices of refraction.

Wave Interference

• Wave interference occurs when two waves make contact.
• There are two types of wave interference: constructive and destructive interference.

Doppler Effect

• The Doppler effect is the apparent change in the frequency of waves emitted by a wave source when it and/or the observer are moving toward or away from each other.
• The actual frequency does not change, but the apparent frequency of the waves is changed.

Nature of Light

• For hundreds of years, physicists debated whether light is a wave or a particle.
• The debate was resolved with the discovery of wave-particle duality, which states that light has both properties.

Properties of Light

• The properties of light are intensity (or brightness), direction, frequency (or color), and polarization.

Reflection and Refraction

• Reflection is when light bounces off shiny, reflective surfaces.
• Refraction is when light bends when it moves from one medium to another.

Diffraction

• Diffraction is the process by which a beam of light is spread out as it passes through an aperture or across the edge of an object.
• When light passes through an aperture and diffracts, it produces an interference pattern.

Conservation of Energy

• Energy is neither created nor destroyed, only transformed from one type to another
• Gravitational potential energy (GPE) is based on an object's height and calculated using the equation: GPE = mgh
• Kinetic energy is greater if an object moves faster and calculated using the equation: KE = 1/2mv^2

Power

• Power is the rate of work done over time, measured in units of horsepower (Hp), Watts (W), or joules per second (J/s)
• Mechanical power is the output of work done by a system over time, while electrical power is the amount of energy moved within a circuit over time
• Torque and angular velocity can be used to calculate mechanical power, while voltage and current can be used to calculate electrical power

Thermal Energy

• Thermal energy is the energy an object or system has due to the movement of its particles
• Thermal energy is both a type of kinetic energy and capable of doing work
• Thermal energy can be transferred through convection, conduction, and radiation

Radiant Energy

• Radiant energy is a type of energy that can transfer through empty space or a vacuum
• Radiant energy comes in the form of electromagnetic radiation and gravitational radiation
• All radiant energy travels at the speed of light, or approximately 300,000,000 meters per second in a vacuum
• Radiometry can be used to measure radiation flux in units of watts or joules per second

Chemical Energy

• Chemical energy is the energy stored in the bonds of chemical compounds
• Chemical energy is a form of potential energy
• Breaking atomic bonds requires energy, while forming new bonds releases energy
• Exothermic reactions involve substances that release more energy than they absorb, while endothermic reactions absorb more energy than they release

Nuclear Energy

• Nuclear energy is a form of energy released from the nucleus of atoms
• Nuclear energy is released through fission reactions when large atoms are split apart, or fusion reactions when small atoms are fused together
• Einstein's work on mass-energy equivalence helps explain how nuclear energy is possible

Heat and Temperature

• Heat is a form of energy that can be transferred from one body to another
• Heat causes thermal expansion of objects over the length, area, or volume dimensions
• The heat energy required to raise the temperature of a substance depends on the mass of the substance, the nature of the substance, and the temperature difference
• The heat capacity or thermal capacity of a body is the quantity of heat energy that results in a unit change in the temperature of the body

Energy and Living Organisms

• Energy is the ability to do work
• All living organisms require energy for survival and reproduction
• The sun provides energy for the entire planet, which is then transformed into more usable forms for living organisms
• Plants utilize photosynthesis to produce sugar and oxygen from carbon dioxide and water
• Cellular respiration is the synthesis of ATP using energy released by the breakdown of sugar to carbon dioxide and water

Waves

• A wave is a vibration or disturbance that travels from one point to another and carries energy
• Wave propagation refers to the movement of waves
• All waves have frequency, amplitude, wavelength, and wave speed
• Wave speed is determined using the equation: v = fλ
• Factors that affect wave speed include tension, rigidity, density, and temperature

Sound Waves

• Sound is a type of energy that vibrates and moves in waves
• Sound waves are longitudinal waves that require a medium in which to travel
• The amplitude of a sound wave is a reflection of how much energy is carried, which contributes to the intensity of the sound
• The frequency of a sound wave is perceived as pitch
• Humans can detect pitches within the acoustic range of 20 to 20,000 Hz

Electromagnetic Radiation

• Electromagnetic radiation is a wave that propagates through space, carrying energy at the speed of light
• Electromagnetic radiation includes seven types of light: radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays
• The electromagnetic spectrum is listed in order from lowest frequency to highest and from longest wavelength to shortest

Color

• Color is a form of electromagnetic radiation
• Human eyes are specialized organs that detect electromagnetic radiation
• The visible light spectrum is normally divided into seven pure spectral colors: red, orange, yellow, green, blue, indigo, and violet
• Each frequency corresponds to a particular color

Resonance

• Resonance is an occurrence in physics where a specific frequency of vibration causes a nearby object to increase the amplitude at which it vibrates

• Resonant frequency is the frequency at which an object naturally vibrates

• Resonance occurs in RLC circuits, musical instruments, and light waves### Interaction of Light with Objects

• When a light wave's frequency matches the resonance frequency of an object, absorption occurs.

• If all frequencies of the light wave match the resonance frequency of the object, the light wave will be completely absorbed.

Classification of Objects

• Objects can be classified as opaque, transparent, or translucent based on how they interact with light.
• Opacity is the degree to which an object blocks light from passing through.

Absorption and Reflection

• Light waves are absorbed when their frequency matches the natural frequency of the object they hit.
• When the frequency of the light wave does not match the natural frequency of the object, it is reflected.
• There are two types of reflection: specular and diffuse.

Transmission

• When light waves pass completely through an object, it is called transmission.
• Energy from the light wave passes to nearby atoms until it exits the other side of the material.
• Snell's Law states that the speed of the light wave remains constant in this situation.

Refraction

• When light waves do not completely pass through an object, but bend as they enter it, it is called refraction.
• Refraction occurs if the light wave enters an object with a different density.
• The bending of light waves is called refraction, and the object is translucent.

Refraction and Snell's Law

• When a wave passes from one medium to another, it bends, and this is known as refraction.
• Snell's Law states that the ratio of the angles of incidence and refraction is equal to the inverse ratio of the indices of refraction.

Wave Interference

• Wave interference occurs when two waves make contact.
• There are two types of wave interference: constructive and destructive interference.

Doppler Effect

• The Doppler effect is the apparent change in the frequency of waves emitted by a wave source when it and/or the observer are moving toward or away from each other.
• The actual frequency does not change, but the apparent frequency of the waves is changed.

Nature of Light

• For hundreds of years, physicists debated whether light is a wave or a particle.
• The debate was resolved with the discovery of wave-particle duality, which states that light has both properties.

Properties of Light

• The properties of light are intensity (or brightness), direction, frequency (or color), and polarization.

Reflection and Refraction

• Reflection is when light bounces off shiny, reflective surfaces.
• Refraction is when light bends when it moves from one medium to another.

Diffraction

• Diffraction is the process by which a beam of light is spread out as it passes through an aperture or across the edge of an object.
• When light passes through an aperture and diffracts, it produces an interference pattern.