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Activities

Computer Simulation

30 min.

Blackbody PhET
Students use a PhET to explore properties of the Planck distribution.
  • blackbody
    Found in: Contemporary Challenges course(s)
These notes from the fourth week of https://paradigms.oregonstate.edu/courses/ph441 cover blackbody radiation and the Planck distribution. They include a number of small group activities.

Small Group Activity

30 min.

Grey space capsule
In this small group activity, students work out the steady state temperature of an object absorbing and emitting blackbody radiation.

Small Group Activity

30 min.

Energy radiated from one oscillator
This lecture is one step in motivating the form of the Planck distribution.

Small Group Activity

10 min.

Thermal radiation at twice the temperature
This small group activity has students reasoning about how the Planck distribution shifts when the temperature is doubled. This leads to a qualitative argument for the Stefan-Boltzmann law.

Small Group Activity

30 min.

Black space capsule
In this activity, students apply the Stefan-Boltzmann equation and the principle of energy balance in steady state to find the steady state temperature of a black object in near-Earth orbit.
This very short lecture introduces Wein's displacement law.

Problem

Heat shields
A black (nonreflective) sheet of metal at high temperature \(T_h\) is parallel to a cold black sheet of metal at temperature \(T_c\). Each sheet has an area \(A\) which is much greater than the distance between them. The sheets are in vacuum, so energy can only be transferred by radiation.
  1. Solve for the net power transferred between the two sheets.

  2. A third black metal sheet is inserted between the other two and is allowed to come to a steady state temperature \(T_m\). Find the temperature of the middle sheet, and solve for the new net power transferred between the hot and cold sheets. This is the principle of the heat shield, and is part of how the James Web telescope shield works.
  3. Optional: Find the power through an \(N\)-layer sandwich.