Unit 4 - Waves

Question 1

Medium

Answer 1

Subtance which wave moves

Question 2

Wavefront

Answer 2

Leading edge of wave

Question 3

Incident Wave

Answer 3

Wave moving away from source to barrier

Question 4

Reflected Wave

Answer 4

Wave moving away from barrier

Question 5

Phase

Answer 5

Identical point on diff wave

Question 6

Transverse Wave

Answer 6

Moving perpendicular to medium

Question 7

Longitudinal Wave

Answer 7

Moves parallel to medium

Question 8

Oscillation (Period)

Answer 8

• Repetitive back & forth motion
• = frequency

Question 9

Principle of Superposition

Answer 9

When 2+ waves overlap, resultant d = to sum of of individual disturbances (pulse a + pulse b = new pulse)

Question 10

Constructive Interference

Answer 10

• Pulses overlap making bigger amp
• Crest = +
• Trough = -

Question 11

Standing Wave

Answer 11

When 2 waves w/same f & amp, moving in diff dir interfere

Question 12

In-phase

Answer 12

Crests/troughs of waves have same point in medium

Question 13

Out of phase

Answer 13

Crest from 1 wave has same point in medium as trough from 2nd one

Question 14

Resonance

Answer 14

Increase of amp bc of nrg transfer in phase w/natural f of wave (think of swings, how sound resonances)

Question 15

Sounds are longitidinal waves with

Answer 15

• Compressions (high pressure, crests)
• Rarefactions (low pressure, troughs)

Question 16

Wavelength of Sound Wave

Answer 16

D between successive compressions/rarefactions

Question 17

Speed of Sound depends on medium

Answer 17

• Stiffer the medium, the faster
• Warmer air makes faster sound waves

Question 18

On the dB scale, every 3dB increase

Answer 18

• Doubles intensity
• 10 dB = 10 times increase

Question 19

Nodes are

Answer 19

At every half-wavelength from the end where the wave is reflected

Question 20

Simpliest Vibrations

Answer 20

• 1 antinode
• L = 0.5 wavelength

Question 21

Overtones

Answer 21

Frequencies above fundamental frequencies

Question 22

Harmonic Frequencies

Answer 22

Resonant frequencies w/whole multiples of fundamental frequency

Question 23

Closed End Air Columns

Answer 23

1/4

Question 24

Open End Air Columns

Answer 24

1/2 (cosine)

Question 25

Refrigerators & Conditioners

Answer 25

1. Expansion valve turns high pressured refrigerant into cold low pressure 2. Evaporator vaporizes rest, absorbing heat from food 3. Warm vapour enters compressor, increasing pressure 4. High hot pressure enters condenser into warm liquid