Catch the false line about light

Exercise and reference answers

Questions

1. False statement

   Doubling the brightness doubles the energy each electron carries off.

   Statements

   1. The kinetic energy of an ejected electron is set by the light's frequency.
   2. Doubling the brightness doubles the energy each electron carries off.
   3. Doubling the brightness raises the number of electrons ejected.

2. False statement

   A bright enough beam below the threshold frequency still ejects electrons.

   Statements

   1. Each photon carries an energy fixed by its own frequency.
   2. Below the threshold frequency no electron leaves the metal at all.
   3. A bright enough beam below the threshold frequency still ejects electrons.

3. False statement

   Long wavelength radiation crawls through vacuum more slowly than short.

   Statements

   1. Long wavelength radiation crawls through vacuum more slowly than short.
   2. Photons of shorter wavelength carry more energy than longer ones.
   3. Wave number counts how many waves fit into one unit of length.

Instructions

Each set of three lines about light striking a metal holds one that is wrong. Tap that line.

Explanation