Early Quantum Theory

1) The walls of a blackbody cavity are at a temperature of 27^o C. What is the frequency of the radiation of maximum intensity?

2) Assume that a 100 – W light bulb gives off 2.50% of its energy as visible light. How many photons of visible light are given off in 1.00 min? (Use an average visible wavelength of 550 nm)

3) What is the energy of photons (joules) emitted by an 107.5-MHz FM radio station?

4) What is the longest wavelength of light that will emit electrons from a metal whose work function is 3.50 eV?

5) A metal with a work function of 2.40 eV is illuminated by a beam of monochromatic light. If the stopping potential is 2.5V, what is the wavelength of the light?

6) What is the de Broglie wavelength of a 1000 kg car moving at a velocity of 25 m/s?

7) A hydrogen atom in its ground state is excited to the n = 5 level. It then makes a transition directly to the n = 2 level before returning to the ground state.

a) What are the wavelengths of the emitted photons?
b) Would any of the emitted wavelengths be in the visible region?

8) What is the longest wavelength light capable of ionizing a hydrogen atom in the ground state?