Physics 6.5

1. Physics 6.5

2. Quantum Theory • Atoms can only give off or absorb a discrete amount of energy. • This energy is given off or absorbed as light or electromagnetic waves. • Energy of a photon = h Planck's constant times the frequency (f).

3. ??? • A photon with a frequency of 2.00 E19 collides with an electron at rest. • Calculate the total energy of the photon. • What is the total energy of the two particle system after the collision?

4. ??? • The light of the “alpha line” in the Balmer series of the hydrogen spectrum has a wavelength of 6.58 E-7 meter. • Calculate the energy of the “alpha line” photon in joules. show all work, including the equation and substitution with units.) • What is the energy of an “alpha line” photon in electron volts? • E = hc/λ

5. ??? • An electron in a hydrogen atom drops from the n=3 energy level to the n=2 energy level. Energy of the emitted photon =1.89eV or 3.02 E-19J. Calculate the frequency of the emitted radiation. (show all work, including the equation an substitution with units.)

6. The Atom • The strong nuclear force holds protons and neutrons together over a short range. • Antimatter is made up of antiparticles. Antiproton, antineutron, and positrons are all antiparticles.

7. Einstein • Einstein’s theory E = mc² shows that mass changes into energy. • To find the amount of energy produced, use the equation E = mc².

8. ??? • The positron has the same mass as the electron. Calculate how many joules of energy are released when they annihilate. (show all work, units) • What conservation law prevents this from happening with two electrons?

9. Particle Physics • Basically, you have Hadrons and Leptons. • Hadrons include protons and neutrons, and are made up of 3 quarks. • Leptons include electrons and positrons and have very little mass. • Antiquarks have the opposite charge of their counterpart quark.

10. Standard model of particle physics

11. Which particle would generate the greatest amount of energy if its entire mass were converted into energy? • electron • proton • alpha particle • Neutron • Answer3

12. As the wavelength of a photon increases, its momentum • decreases • increases • remains the same • Answer1

13. An electron in the c level of a mercury atom returns to the ground state. Which photon energy could not be emitted by the atom during this process? • 0.22 eV • 4.64 eV • 4.86 eV • 5.43 eV • Answer4

14. The strong force is the force of • repulsion between protons • attraction between protons and electrons • repulsion between nucleons • attraction between nucleons • Answer4

15. A tritium nucleus consists of one proton and two neutrons and has a total mass of 3.0170 atomic mass units.  What is the mass defect of the tritium nucleus? • 0.0014 u • 0.0077 u • 1.0010 u • 2.0160 u • Answer2

16. The charge of an antistrange quark is approximately • +5.33 × 10-20 C • -5.33 × 10-20 C • +5.33 × 1020 C • -5.33 × 1020 C • Answer1

17. The diagram represents alpha particle A approaching a gold nucleus.  D is the distance between the path of the alpha particle and the path for a head-on collision. If D is decreased, the angle of deflection (θ) of the alpha particle would • decrease • increase • remain the same • Answer2

18. A lithium atom consists of 3 protons, 4 neutrons, and 3 electrons. This atom contains a total of • 9 quarks and 7 leptons • 12 quarks and 6 leptons • 14 quarks and 3 leptons • 21 quarks and 3 leptons • Answer4