Question

What did experiments by Hallwachs and Lenard show about light and metals?

Options

• Light prevents negatively charged particles from leaving metals

• Light can cause the emission of negatively charged particles from metals

• All metals respond to the same minimum frequency

• Metals emit negatively charged particles only after light is removed

Answer 1

Hallwachs and Lenard found that illumination could release negatively charged particles from metals. This finding became a major clue in the development of modern quantum physics.