Electrons are emitted from a surface when light of wavelength 500 nm is shone on the surface but electrons are not emitted for longer wavelengths of light. The work function of the surface is
A) 5.0 eV.
B) 0.60 eV.
C) 2.5 eV.
D) 4.0 eV.
E) 0.40 eV.
Question 2
When an electron collides with a positron the two particles
A) fuse to form a heavier particle
B) bounce off each other
C) are destroyed, producing a pair of high-energy gamma rays
D) are destroyed, producing another pair of particles