Waves, sound and light

Question 1

Define pulse

Answer 1

A single disturbance that moves along or through a medium, while the overall medium does not change.

Question 2

Medium

Answer 2

Material through which a wave travels

Question 3

Amplitude

Answer 3

Maximum distance that particles move from their rest position.

Question 4

Transverse wave

Answer 4

Wave where movement of particles of the medium is perpendicular to the direction of propagation of the wave.

Question 5

Wavelength

Answer 5

Distance between any two adjacent points in phase

Question 6

Period

Answer 6

Time taken for 2 successive crests or troughs to pass a fixed point

Question 7

Frequency

Answer 7

Number of successive crests or troughs passing a given point in 1 second

Question 8

Longitudinal wave

Answer 8

Wave where the particles in the medium move parallel to the direction of propagation of the wave

Question 9

Compression

Answer 9

Region in a longitudinal wave where the particles are closest together

Question 10

Rarefaction

Answer 10

Region in a longitudinal wave where particles are furthest apart

Question 11

Sound Waves

Answer 11

• Pressure waves
• Travels fastest in solids, slightly slower in liquids and
  slowest in gases
• Compressions and rarefactions are created as the sound source vibrates
• source vibrates longitudinally and the longitudinal motion of air produces pressure fluctuations

Question 12

Speed of sound

Answer 12

• Dependent on medium
• Faster in denser substances
• Depends of temperature
• Influenced by pressure of medium

Question 13

Reflection and echoes

Answer 13

• When sound waves collide with an object they are reflected

- sound is reflected in large open spaces where there is a very large object present causes an echoe

Question 14

Pitch

Answer 14

• Depends on frequency
• High frequency = higher pitch
• Low frequency = Low pitch

Question 15

Loudness

Answer 15

• Depends on Amplitude
• Larger amplitude = louder sound
• Smaller amplitude = softer sound
• Also dependent on ear sensitivity

Question 16

Ultrasound

Answer 16

• Frequency between 20-150 kHz

- High frequency and short wavelengths

Question 17

Uses of Ultrasound

Answer 17

• Bats send out ultrasound signals which are reflected to detect positions of objects
• Dolphins send out ultrasound signals to detect objects further away
• Detects weak spots in metal objects
• Thickness of metals and plastics
• Clean delicate mechanisms of old fashioned watches

Question 18

Noise

Answer 18

Sound consisting of a large number of unrelated different frequencies

Question 19

Electromagnetic Radiation

Answer 19

No medium required wave

Question 20

How does EM radiation work?

Answer 20

• Result of accelerating charges
• Magnetic field produced around moving electric charge
• Oscillating magnetic field in turn producesa magnetic field in a plane at rights angles to it, which again produces an oscillating magnetic field
• Thus, EM radiation produced by magnetic and electric fields repeatedly creating each other

Question 21

Order of EM radiation

Answer 21

Radio waves, Microwaves, infrared, visible spectrum, ultraviolet, X rays, Gamma rays

Question 22

Photon

Answer 22

Energy packet of light