B.1 Thermal energy transfersIB Physics HL: Flashcards

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How is kelvin temperature related to Celsius temperature?

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How is kelvin temperature related to Celsius temperature?: T(K) = θ(°C) + 273; a temperature change is the same in both.
What does the Kelvin temperature of a gas measure?: The average random kinetic energy of its particles, Ek = (3/2)kBT.
Define internal energy.: Total intermolecular potential energy + total random kinetic energy of the molecules.
What happens to temperature during a phase change?: It stays constant; the energy changes intermolecular potential energy.
Define specific heat capacity.: The energy needed to raise the temperature of 1 kg of a substance by 1 K.
Define specific latent heat.: The energy needed to change the phase of 1 kg of a substance at constant temperature.
Explain conduction in terms of particles.: Faster-vibrating particles pass kinetic energy to neighbours through collisions, from hot to cold.
Give the equation for the rate of conduction.: ΔQ/Δt = kAΔT/Δx.
What causes convection?: Density differences: warm fluid expands, becomes less dense and rises; cool, denser fluid sinks.
State the Stefan–Boltzmann law.: L = σAT⁴ for a black body.
Define apparent brightness.: Power received per unit area at the observer, b = L/(4πd²).
State Wien's displacement law.: λmax T = 2.9 × 10⁻³ m K.
A star is red and very luminous. What does this suggest about its size?: It is cool (long λmax), so to be very luminous it must have a very large surface area — a giant.