Quantum

Question 1

How can the energy of a photon be expressed?

Answer 1

E=cp=hf=hc/lambda

Question 2

How can the momentum of a photon be expressed in terms of its wavelength?

Answer 2

p=h/lambda

Question 3

What is the wave function of a particle?

Answer 3

The wave function is a complex probability distribution, that can be operated on the extract information about the particle.

Question 4

What does it mean that the wave function should be normalised?

Answer 4

The total integral of (the complex conjugate of the wave function * the wave function) with respect to position should equal 1.

Question 5

What is an operator useful for?

Answer 5

An operator for an observable allows the expectation value of that observable to be extracted from the wave function.

Question 6

How can an operator be used to extract the expectation value of an observable?

Answer 6

The expectation value = the integral of (the complex conjugate of the wave function * the operator operating on the wave function)

Question 7

What does h-bar denote?

Answer 7

h/2pi (where h is the planck constant)

Question 8

What is Heisenberg’s uncertainty principle?

Answer 8

The product of the standard deviation of position and the standard deviation of momentum for a particle is greater than or equal to h-bar / 2.

Question 9

What is the energy-time uncertainty relation?

Answer 9

The product of the standard deviation of energy and the standard deviation of time is approx greater than h-bar.