4.4 Waves

Question 1

The frictional force experienced by an object travelling through a fluid (a liquid or a gas, eg: air).

Answer 1

Waves transfer energy sans any overall movement of matter.

Question 2

Sound energy: longitudinal or transverse?

Answer 2

Longitudinal;

Question 3

What are progressive waves?

Answer 3

A progressive wave is any wave that transfers energy through space and may be longitudinal or transverse in nature.

Question 4

What is the equation that links the frequency and period of a wave?

Answer 4

f=1/t

Question 5

Produce two equations that one may use to find the intensity of a wave.

Answer 5

Intensity = power/ area
this gives
I=P/A

Question 6

What is the relationship that links the amplitude of a wave and the intensity? Link power into this.

Answer 6

The power of a wave is proportional to the square of its amplitude, via Iis proportional to A^2.

Question 7

When does light refract? What law is this demonstrated by?

Answer 7

1. When going from one optically dense medium into another;
2. Snell’s law describes this:
   n1sin(theta)1=n2sin(theta)2

Question 8

When does light undergo total internal reflection? Link this to the critical angle and give an equation that describes this relationship.

Answer 8

1. When travelling from a more to a less optically dense material; IF THE ANGLE OF INCIDENCE IS GREATER THAN THE CRITICAL ANGLE, C
2. sinC=1/n

Question 9

What is the principle of superposition and what does this produce?

Answer 9

1. It says: when two or more coherent waves overlap or superpose, the resultant waveform will have an amplitude equal to the vector sums of their individual amplitudes.
2. This produces constructive and destructive waves: based on their phase differences

Question 10

What is the official term that describes the experiment which used diffraction gratings? What was the purpose of this experiment?

Answer 10

1. Young’s double slit experiment;

2. This was used to obtain a value for the wavelength of light.

Question 11

When can waves be described to have nodes, antinodes, nodes of vibration and harmonics?

Answer 11

When stationary or standing waves are set up on strings or in air columns interfere and superpose;

Question 12

How can one calculate the speed of sound in air?

Answer 12

By using a tuning fork and a resonance tube to produce standing waves;