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Practice Final Spring 2010

Final: 5/11/2010, 11:15-1:45 Javits 1051. Suppose that gasoline is ethane (

C2H

6); how many kilograms ofCO

2are

produced by burning 4 kg (about one gallon) of ethane?

2. What did Einstein say about gravity and acceleration in his theory ofGeneralTheory of Relativity?

3. Draw a wave function for an energy E in the potential shown below.a.

b. What is the wavelength of an electron with a kinetic energy of 5 eV?c. What is the momentum (in Kg-m/s) of an electron with a kinetic energy of 5eV?

d. What is the uncertainty in the position of the electron with 5 eV kinetic energy

e. At what angle will the first (n=1) Bragg reflection occur when 5 eV (kinetic

energy) electrons are incident upon a material where atomic planes are spaced

1.01010m apart?

f. What is the probability that the 5 eV electron will tunnel through a barrier of 8

eV that is 1109m thick?4. a. What are the first three energy levels of Cl atom if we consider it to be a

hydrogen-like atom?

b. What photon energy is needed to cause an electron to jump from the 1st to freespace detached from the nucleus (

n =)?

c. What is the angular momentum in the z-direction of the 3d state.

d. Can a photon excite an electron to jump from the 1s state to the 2s state?5. a. According to the Drude model what is the conductance, , of a material

containing a mobile electron density of n =1021cm3 and with a lifetime (the time

between collisions) of1014 s? (note use the electronic mass of

me= 0.511MeV /C

2 and remember the value of eV is the same as an electronic

charge, 1.61019C times the voltage applied, V).b. What current could be produced by applying 1 volt to a piece of round wire 1

cm in diameter and 2 cm long (please answer in amps) hint: 1amp = 1Cs

c. Consider the nuclear reaction: n+3

6Li

2

4He+

1

3H E= 4.8MeV

a. Which side of the equation (left or right) weighs more?b. What are the number of neutrons and protons on each side of the

equation

c. Where did the mass change (and/or) energy release come from?

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