Lecture 2

Question 1

Longer cavity of sound travel means

Answer 1

Lower sounds since

Resonant frequency decreased and wavelength increased

Question 2

Till slide 10

Answer 2

Ask what is supposed to tell us

Question 3

In making the wave equation what are the assumptions we use

Answer 3

That the wave does not change over time, it it’s resonating (time independent)

The wave starts at the boundary x=0

The wave is composed of sin and cos functions

Question 4

What is the simplified wave equation before the boundary conditions

Answer 4

= C cos (kx) + D sin (kx)

Question 5

What are the boundary conditions for the wave

Answer 5

At x=0 and L=0, wave function is zero

It can’t exist outside these boundary’s

Question 6

Because of the boundary limit, what does the wave equation then become

Answer 6

= D sin (kx)

Because the C constants has to always equal zero to fulfil the boundary rule

Question 7

What does the second boundary condition do the the wave equation

Answer 7

At x=L wave function is also zero so

D sin (kL) has to all equal zero at x=L

Only when kL= n(pi) is the whole thing zero

Question 8

What can kL= n(pi) help us with in the wave equation

Answer 8

Can isolate for k

k=n(pi)/L

Then plug into wave equation

D sin (x n(pi)/L)

Question 9

What is the lowest number that n can be in the wave equation and why

Answer 9

1 because that gives half a wave, any lower and it is not a wave anymore

Question 10

What is a node

What is an antinode

Answer 10

Node is the n-1

Antinode is the n

Ex. If n=2 that’s a full wave that has one node and two antinodes

Question 11

Slide 23

Answer 11

What about carbon bond is important

Question 12

What is particle in a box

Answer 12

When the electron is more and more restricted/confined in a boundary, we see it as a wave instead of particle

Question 13

What is the Schrödinger wave equation

Answer 13

H | ¥ = E |¥

This means the H of the wave function equals the E of the wave function

It’s the quantum interpretation of the matter wave

Question 14

What is H and E in the schroedinger wave equation

Answer 14

H is the kinetic and potential energy

E is the observable energy

Question 15

Learn how to make simplified version of shrodinger equation using the boundary conditions

Answer 15

Slide 30 and tut 2

Question 16

Is relation to the Schrödinger equation, n=1 is

Answer 16

The ground state energy, can’t go lower

Question 17

Where is the highest probability of finding the electron in its wave

Least

Answer 17

At the antinodes

At the nodes (not the boundary’s because this are not nodes)

Question 18

How do you find energy levels of the piaB wave

Answer 18

Since E0 is when n=1 and there is half wave,

n=2 is E0(2^2) so E1= E0(4)

Then E0(3^2) so. E2= E0(9)

Question 19

Slides 37 and 38

Answer 19

Ask for explain

Question 20

What does Eg + Ec = E photon mean

Answer 20

The normal energy gap between levels plus the addition energy due to being confined makes up the energy of the releases photon

This means that electrons gain more energy (Ec) than normal from being trapped between boundary’s

Question 21

Slide 39

Answer 21

Diff coloured things explain why