20 Practice Questions for HSC Physics Module 7: The Nature of Light

Light: Wave Model

Question 6

A grating is lit up by a parallel beam of light with a wavelength of 500nm. The first order maximum is in a direction that makes an angle of 20º with the parallel.

 

Conduct investigations to analyse quantitatively the interference of light using double slit apparatus and diffraction gratings ?sin?=?? (ACSPH116, ACSPH117, ACSPH140)

Question 7

Explain why the transverse wave model for electromagnetic radiation is incorrect, making a reference to polarisation.

 

Conduct investigations quantitatively using the relationship of Malus’ Law ?=?max???2? for plane polarisation of light, to evaluate the significance of polarisation in developing a model for light (ACSPH050, ACSPH076, ACSPH120)  

Light: Quantum Model

Question 8

Draw a graph to show a normal black body radiation curve an on the same graph draw a radiation curve predicted by classical theory. Explain the differences between the relationships.

 

Analyse the experimental evidence gathered about black body radiation, including Wien’s Law related to Planck’s contribution to a changed model of light (ACSPH137)

Question 9

The peak frequency of cosmic background radiation is around 160 GHz. Using the information provided, what is the temperature of outer space?

 

Analyse the experimental evidence gathered about black body radiation, including Wien’s Law related to Planck’s contribution to a changed model of light (ACSPH137)

Question 10

To what extent was Einstein’s contribution to quantum theory and its relation to black body radiation ground-breaking?

 

Analyse the photoelectric effect ?max=ℎ?−? as it occurs in metallic elements by applying the law of conservation of energy and the photon model of light (ACSPH119)

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Question 11

Explain how using the stopping voltage of a beam of photoelectrons enables people to calculate the kinetic energy of them as well as the work function of the material emitting the photoelectrons.

 

Analyse the photoelectric effect ?max=ℎ?−? as it occurs in metallic elements by applying the law of conservation of energy and the photon model of light (ACSPH119)

Question 12

If a photon carries 5.7 eV of energy, how much energy does it carry in joules?

 

Analyse the photoelectric effect ?max=ℎ?−? as it occurs in metallic elements by applying the law of conservation of energy and the photon model of light, (ACSPH119)

Light and Special Relativity

Question 13

Explain the meaning of “inertial frames of reference”.

 

Analyse and evaluate the evidence confirming or denying Einstein’s two postulates:

• the speed of light in a vacuum is an absolute constant
• all inertial frames of reference are equivalent

(ACSPH131)

Question 14

What were the two postulates proposed by Einstein in his theory of special relativity?

 

Analyse and evaluate the evidence confirming or denying Einstein’s two postulates:

• the speed of light in a vacuum is an absolute constant
• all inertial frames of reference are equivalent

(ACSPH131)

Question 15

Explain the consequences of the assumption that the speed of light is constant in all frames of reference.

 

Analyse and evaluate the evidence confirming or denying Einstein’s two postulates:

• the speed of light in a vacuum is an absolute constant 
• all inertial frames of reference are equivalent

(ACSPH131)

Question 16

A stationary observer is outside the solar system and is watching the Earth as a spaceship is travelling away from Earth. How would the observer perceive time on Earth and on the spaceship? Explain your reasoning.

 

Investigate the evidence, from Einstein’s thought experiments and subsequent experimental validation, for time dilation and length contraction, and analyse quantitatively situations in which these are observed, for example:

• observations of cosmic-origin muons at the Earth’s surface
• atomic clocks (Hafele–Keating experiment)
• evidence from particle accelerators
• evidence from cosmological studies

Question 17

Two UFOs are moving towards each other. UFO A is moving at 0.6c and UFO B is moving at 0.9c. What would be the relative speed of the rockets if it was measured by a stationary observer not on either UFO?

 

Investigate the evidence, from Einstein’s thought experiments and subsequent experimental validation, for time dilation and length contraction, and analyse quantitatively situations in which these are observed, for example:

• observations of cosmic-origin muons at the Earth’s surface
• atomic clocks (Hafele–Keating experiment)
• evidence from particle accelerators
• evidence from cosmological studies

Question 18

Describe one piece of evidence that supports time dilation, one piece of evidence that supports length contraction and one piece of evidence that supports mass increase.

 

Investigate the evidence, from Einstein’s thought experiments and subsequent experimental validation, for time dilation and length contraction, and analyse quantitatively situations in which these are observed, for example:

• observations of cosmic-origin muons at the Earth’s surface
• atomic clocks (Hafele–Keating experiment)
• evidence from particle accelerators
• evidence from cosmological studies

Question 19

How did the Michelson-Morley experiment give evidence for Einstein’s proposal of the speed of light being constant in all frames of reference?

 

Analyse and evaluate the evidence confirming or denying Einstein’s two postulates:

• the speed of light in a vacuum is an absolute constant
• all inertial frames of reference are equivalent

(ACSPH131)

Question 20

Explain, using equations, why the speed of light cannot be exceeded.

 

Describe the consequences and applications of relativistic momentum with reference to:

• the limitation on the maximum velocity of a particle imposed by special relativity (ACSPH133)