Modern Physics
2nd Edition
ISBN: 9780805303087
Author: Randy Harris
Publisher: Addison Wesley
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Question
Chapter 4, Problem 53E
(a)
To determine
The reason why the energy of the particle cannot be to zero.
(b)
To determine
The reasonable assumption about typical value of momentum and find the particle’s minimum possible energy.
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(d) Prove that for a classical particle moving from left to right in a box with constant
speed v, the average position = (1/T) ff x(t) dt = L/2, where T L/v
is the time taken to move from left to right. And = : (1/T) S²x² (t) dt
L²/3. Hint: Only consider a particle moving from left x = 0 to right x = L
=
and do not include the bouncing motion from right to left. The results for left
to right are independent of the sense of motion and therefore the same results
apply to all the bounces, so that we can prove it for just one sense of motion.
Thus, the classical result is obtained from the Quantum solution when n >> 1.
That is, for large energies compared to the minimum energy of the wave-particle
system. This is usually referred to as the Classical Limit for Large Quantum
Numbers.
= =
An electron having total energy E 4.60 eV approaches a rectangular energy barrier with U■5.10 eV and L-950 pm as shown in the figure below. Classically, the electron cannot pass through the barrier
because E < U. Quantum-mechanically, however, the probability of tunneling is not zero.
Energy
E
U
0
i
(a) Calculate this probability, which is the transmission coefficient. (Use 9.11 x 10-31 kg for the mass of an electron, 1.055 x 10-34] s for h, and note that there are 1.60 x 10-19
J per eV.)
(b) To what value would the width L of the potential barrier have to be increased for the chance of an incident 4.60-eV electron tunneling through the barrier to be one in one million?
nm
For ultrarelativistic particles such as photons or high-energy electrons, the relation between energy and momentum is not E = p2/2m but rather E = pc. (This formula is valid for massless particles, and also for massive particles in the limit E » mc2.)
Estimate the minimum energy of an electron confined inside a box of width 10-15 m. It was once thought that atomic nuclei might contain electrons; explain why this would be very unlikely.
Chapter 4 Solutions
Modern Physics
Ch. 4 - Prob. 1CQCh. 4 - Prob. 2CQCh. 4 - Prob. 3CQCh. 4 - Prob. 4CQCh. 4 - Prob. 5CQCh. 4 - Prob. 6CQCh. 4 - Prob. 7CQCh. 4 - Prob. 8CQCh. 4 - Prob. 9CQCh. 4 - Prob. 10CQ
Ch. 4 - Prob. 11ECh. 4 - Analyzing crystal diffraction is intimately tied...Ch. 4 - The setup depicted in Figure 4.6 is used in a...Ch. 4 - Prob. 14ECh. 4 - Prob. 15ECh. 4 - Prob. 16ECh. 4 - Prob. 17ECh. 4 - Prob. 18ECh. 4 - Prob. 19ECh. 4 - Prob. 20ECh. 4 - Prob. 21ECh. 4 - Prob. 22ECh. 4 - Prob. 23ECh. 4 - Prob. 24ECh. 4 - Prob. 25ECh. 4 - Prob. 26ECh. 4 - Prob. 27ECh. 4 - Prob. 28ECh. 4 - Prob. 29ECh. 4 - Prob. 30ECh. 4 - Prob. 31ECh. 4 - Prob. 32ECh. 4 - Prob. 33ECh. 4 - Prob. 34ECh. 4 - Prob. 35ECh. 4 - Prob. 36ECh. 4 - Prob. 37ECh. 4 - (a) Experiment X is carried out nine times...Ch. 4 - Prob. 39ECh. 4 - Prob. 40ECh. 4 - Prob. 41ECh. 4 - Prob. 42ECh. 4 - Prob. 43ECh. 4 - Prob. 44ECh. 4 - Prob. 45ECh. 4 - Prob. 46ECh. 4 - Prob. 47ECh. 4 - Prob. 48ECh. 4 - Prob. 49ECh. 4 - Prob. 50ECh. 4 - Prob. 51ECh. 4 - Prob. 52ECh. 4 - Prob. 53ECh. 4 - Prob. 54ECh. 4 - Prob. 55ECh. 4 - Prob. 56ECh. 4 - Prob. 57ECh. 4 - Prob. 59ECh. 4 - Prob. 60ECh. 4 - Prob. 61ECh. 4 - Prob. 62ECh. 4 - Prob. 63ECh. 4 - Prob. 64ECh. 4 - Prob. 65ECh. 4 - Prob. 67ECh. 4 - Prob. 68ECh. 4 - Prob. 71CECh. 4 - Prob. 72CECh. 4 - Prob. 73CE
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