Light falling on a metallic surface of work function 3.0 eV gives energy to the…
PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation
Problem
Light falling on a metallic surface of work function 3.0 eV gives energy to the surface at a rate of 5.0×10−4 W per square metre of the metal's surface. Assume that an electron on the metal surface can absorb energy from an area of about 1.0×10−18 m2.
(1) Estimate how long will it take the electron to absorb an amount of energy equal to the work function.
(2) Outline the implication of this.
(3) Describe how the photon theory of light explains the fact that electrons are emitted almost instantaneously with the incoming photons.