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Questions and Answers
Which constant represents Planck's constant in the formula?
Which constant represents Planck's constant in the formula?
What does Planck's Law describe?
What does Planck's Law describe?
In the formula for spectral radiance in terms of wavelength, what does the term $I_{\lambda, T}$ represent?
In the formula for spectral radiance in terms of wavelength, what does the term $I_{\lambda, T}$ represent?
What is the relationship shown by Planck’s Law regarding temperature?
What is the relationship shown by Planck’s Law regarding temperature?
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Which of the following components is NOT included in the formula for spectral radiance in terms of frequency?
Which of the following components is NOT included in the formula for spectral radiance in terms of frequency?
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What does the Boltzmann constant represent in the context of Planck’s Law?
What does the Boltzmann constant represent in the context of Planck’s Law?
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What happens to the spectral radiance as the wavelength approaches zero?
What happens to the spectral radiance as the wavelength approaches zero?
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How does the speed of light factor into Planck’s Law?
How does the speed of light factor into Planck’s Law?
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What does the Stefan-Boltzmann Law state about a blackbody's emissive power?
What does the Stefan-Boltzmann Law state about a blackbody's emissive power?
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What unit is used to measure the emissive power of a blackbody?
What unit is used to measure the emissive power of a blackbody?
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How does the peak wavelength of radiation emitted by a blackbody change with an increase in temperature?
How does the peak wavelength of radiation emitted by a blackbody change with an increase in temperature?
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What is the approximate value of the Stefan-Boltzmann constant (𝜎)?
What is the approximate value of the Stefan-Boltzmann constant (𝜎)?
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Which equation represents Wien's Displacement Law?
Which equation represents Wien's Displacement Law?
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What is the value of Wien’s displacement constant (𝑏)?
What is the value of Wien’s displacement constant (𝑏)?
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When comparing two blackbodies at different temperatures, how does their emissive power relate?
When comparing two blackbodies at different temperatures, how does their emissive power relate?
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What happens to the emissive power of a blackbody if its absolute temperature is doubled?
What happens to the emissive power of a blackbody if its absolute temperature is doubled?
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What is the primary reason atmospheric pressure decreases with increasing altitude?
What is the primary reason atmospheric pressure decreases with increasing altitude?
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Which of the following is classified as a gaseous contaminant?
Which of the following is classified as a gaseous contaminant?
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What is the standard measurement of atmospheric pressure at sea level in pascals?
What is the standard measurement of atmospheric pressure at sea level in pascals?
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Which of the following is an example of a natural source of atmospheric contaminants?
Which of the following is an example of a natural source of atmospheric contaminants?
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Heavy metals in atmospheric contaminants can include which of the following?
Heavy metals in atmospheric contaminants can include which of the following?
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What does Planck's law state about emissivity and absorptivity of a body in thermal equilibrium?
What does Planck's law state about emissivity and absorptivity of a body in thermal equilibrium?
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Which of the following is NOT a factor affecting solar energy receipts?
Which of the following is NOT a factor affecting solar energy receipts?
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What is the solar constant approximately equal to?
What is the solar constant approximately equal to?
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How does the angle of incidence affect solar radiation absorption?
How does the angle of incidence affect solar radiation absorption?
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Which of these conditions will lead to the least amount of solar energy received on a surface?
Which of these conditions will lead to the least amount of solar energy received on a surface?
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What happens to the effective area exposed to sunlight as the angle of incidence increases?
What happens to the effective area exposed to sunlight as the angle of incidence increases?
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Which phenomenon does not contribute to variations in solar energy receipts?
Which phenomenon does not contribute to variations in solar energy receipts?
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What does the absorptivity (𝛼) of a material refer to?
What does the absorptivity (𝛼) of a material refer to?
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What does atmospheric turbidity specifically measure?
What does atmospheric turbidity specifically measure?
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Which of the following units is NOT used to measure temperature?
Which of the following units is NOT used to measure temperature?
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In the equation $Q = mc_p \Delta T$, what does $Q$ represent?
In the equation $Q = mc_p \Delta T$, what does $Q$ represent?
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What type of heat energy causes a change in temperature without a change in phase?
What type of heat energy causes a change in temperature without a change in phase?
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What phenomenon is associated with the absorption or release of heat energy during a phase change?
What phenomenon is associated with the absorption or release of heat energy during a phase change?
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Which of the options does NOT affect atmospheric turbidity?
Which of the options does NOT affect atmospheric turbidity?
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Which description is TRUE about ground temperature?
Which description is TRUE about ground temperature?
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What is the main process through which sensible heat is transferred?
What is the main process through which sensible heat is transferred?
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Study Notes
Stefan-Boltzmann Law
- The energy emitted by a blackbody is proportional to the fourth power of its absolute temperature.
- The formula for the law is: E = σT⁴
- E is the emissive power (W/m²)
- σ is the Stefan-Boltzmann constant (5.670 x 10⁻⁸ W/m²K⁴)
- T is the absolute temperature (K)
Wein's Displacement Law
- The wavelength at which a blackbody emits radiation most strongly is inversely proportional to its absolute temperature.
- The formula is: 𝜆𝑚𝑎𝑥 = 𝑏/𝑇
- 𝜆𝑚𝑎𝑥 is the peak wavelength (m)
- 𝑏 is Wein's displacement constant (2.898 x 10⁻³ m.K)
- T is the absolute temperature (K)
Planck's Law
- Describes the spectral distribution of electromagnetic radiation emitted by a blackbody in thermal equilibrium.
- Provides the formula for the radiation emitted at each wavelength (or frequency).
- The law states that the emissivity (𝜖) of a body in thermal equilibrium is equal to its absorptivity (𝛼) at every wavelength.
- 𝝐 𝝀, 𝑻 = 𝜶(𝝀, 𝑻)
- 𝝐 𝝀, 𝑻 is the emissivity at a specific wavelength 𝜆 and temperature 𝑇
- 𝜶(𝝀, 𝑻) is the absorptivity at the same wavelength 𝜆 and temperature 𝑇
Solar Radiation
- The solar constant represents the intensity of sunlight arriving at the Earth.
- Approximates to 1,361 W/m²
- The angle of incidence is the angle between a ray of incoming light and the normal to a surface.
- At 0 degrees, the maximum amount of solar energy is absorbed.
- As the angle increases, less energy is absorbed.
- Atmospheric turbidity refers to the degree to which particles and pollutants affect the clarity of the air and the transmission of sunlight.
- It measures the scattering and absorption of light by aerosols in the air (dust, smoke, water vapor, etc).
Temperature
- Measured in Celsius (°C), Fahrenheit (°F), or Kelvin (K).
- A measure of a body's ability to transfer heat energy.
Sensible Heat
- Heat energy that causes a change in temperature without a phase change.
- Transferred through conduction, convection, or radiation.
- The formula is: 𝑄 = 𝒎𝒄𝒑 𝜟𝑻
- Q is sensible heat (J)
- m is the mass of the substance (kg)
- 𝑐𝑝 is the specific heat capacity (J/kg-°C)
- 𝛥𝑇 is the change in temperature (°C or K)
Latent Heat
- The amount of heat absorbed or released during a phase change without a change in temperature.
- It is the heat energy associated with changes in the state of matter (solid, liquid, gas).
Atmospheric Pressure
- Also known as air pressure, is the force exerted by the weight of air molecules above a given point.
- It decreases with increasing altitude.
- Standard atmospheric pressure is 101,325 Pa.
Atmospheric contaminants
- Substances that can harm health, the environment, or both.
- Can be natural or man-made.
- Types:
- Particulate matter (PM)
- Dust, soot, smoke, liquid droplets
- Gaseous contaminants
- CO, NO2, SO2, O3, VOCs
- Heavy metals
- Lead, mercury, cadmium
- Greenhouse gases (GHGs)
- CO2, CH4, N2O
- Particulate matter (PM)
- Sources:
- Natural sources:
- Volcanic eruptions, wildfires, dust storms
- Anthropogenic (man-made) sources:
- Transportation, industries, agricultural activities
- Natural sources:
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Description
Test your knowledge on the Stefan-Boltzmann Law, Wien's Displacement Law, and Planck's Law. Understand the relationship between temperature, wavelength, and energy emission of blackbodies. This quiz covers key formulas and concepts essential in thermodynamics.
