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Formative assessment questions for teaching physics

A2L Item 220

  • Description: Identify the object having lowest resistance.
  • Goal: Reason regarding resistance
  • Source: 283-550 Resistance and geometry
  • Keywords: Electromagnetism, Resistance

The question for students:

Which object below has the lowest resistance? All three have length L and are made out of the same material.

Item220_fig1.gif

  1. #1
  2. #2
  3. #3
  4. Both #1 and #3 have the same, and theirs is less than the resistance of #2.

Commentary for teachers:

Answer

(2) Students should be able to reason that the contribution to the total resistance from a slice of material decreases as the area increases.