Teaching Modern Physics - QuarkNet - Fermilab

Modern Physics
Introduction to Quantum Mechanics
1. Who was Planck and why was he important?
Please attempt every problem.
2. Calculate the energy in Joules and electron volts of a photon whose frequency is:
a. 5 x 10 14 Hz
b. 10 GHz
Calculate the energy in Joules of a photon whose wavelength is 632.8 nm.
3. An electron is stopped by two plates connected to a 1.5 V AA battery.
a. What does the previous statement mean in terms of the electron’s energy?
b. What is the electron’s potential energy in this electric field? Give your answer both in
electron volts and in Joules.
c. What was the electron’s initial kinetic energy?
d. If the mass of an electron is 9.11 x 10 -31 kg (which it is, and also an important number to
remember; it is stored in your calculator under the constants menu—see Me), what was
the electron’s initial velocity when it entered the electric field region?
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