Waves

Question 1

General properties of waves

Answer 1

-transfer energy without transferring matter/ waves are also oscillations or vibrations

Question 2

Wavelength

Answer 2

The distance between the point of a wave and the same point on the next wave
Speed of a wave/frequency

Question 3

Frequency

Answer 3

Number of waves that passes a single point per second
Speed/wavelength

Question 4

Speed

Answer 4

Distance travelled by a wave each second
Frequency x wavelength

Question 5

Time period

Answer 5

Time it a takes to complete a wave or an oscillation
1/frequency

Question 6

Amplitude of a wave

Answer 6

Distance from the center to the crest

Question 7

Transverse waves

Answer 7

-has peaks and troughs
-vibrations are at right angles to the direction of travel
-eg:light

Question 8

Longitudinal wave

Answer 8

-eg: sound waves
-oscillations are parallel to direction of travel

Question 9

Reflection

Answer 9

Change in direction when a wave meets a boundary
Angle of incidence = Angle of reflection
Normal: line at 90* to surface ALWAYS MEASURE ANGLES TO NORMAL

Question 10

Refraction

Answer 10

• change in speed of a wave when there is a change in medium (substance)
• in many cases wave will change direction
• rays enter the surface perpendicular to normal
• frequency stays the same but wavelength changes

Question 11

Diffraction

Answer 11

-Spreading out of a wave when it meets an obstacle. An obstacle can be a gap.
-the narrower the gap, the greater the wavelength, the more diffraction
-frequency, wavelength and speed all stay the same

Question 12

Refractive index in refraction (Snells Law)

Answer 12

n1 x sin Angle1 = n2 x sin Angle 2
N1 is always = to 1 In IGCSE
n = sin (angle of incidence)/ sin (angle of refraction)

Question 13

Refractive index (n) of a medium

Answer 13

Speed of light in vacuum (3.0 x 10 to the power of 8 )/ speed of light in the medium

Question 14

Total internal reflection

Answer 14

When light travels from a more optically dense (=slow) to a les optically dense medium (=fast) there is an angles called CRITICAL ANGLE, BEYOND WHICH NO LIGHT IS TRANSMITTED. All light is reflected.
Critical angle related to refractive index by: n= 1/sin c

Question 15

Converging lenses

Answer 15

Transparent block which brings light rays together at a point called the principal focus by utilizing refraction.
Focal length: distance between the center of the lens and the principal focus.

Question 16

Real images

Answer 16

Formed when distance of the object from the center of the lens is greater than the focal length.

Question 17

Virtual images

Answer 17

Distance of the object from center of the lease is smaller than the focal length.

Question 18

Dispersion of light

Answer 18

When white light passes through a glass prism, it splits up into seven colors. This happens because the different colors travel a different speeds in the glass meaning that they refract by different amounts.

Question 19

Monochromatic light

Answer 19

Light of a single frequency nor wavelength

Question 20

Electromagnetic waves

Answer 20

-Transverse waves
-not need medium
-speed is constant, wavelength decreases, frequency increases.
-THE HIGHER THE FREQUENCY, THE HIGHER THE ENERGY

Question 21

Uses of electromagnetic waves

Answer 21

-radio waves (radio, television communications)
-microwaves (satellite communication, microwave)
-ultraviolet light
-X-rays
-Gamma radiation

Question 22

Sound waves

Answer 22

Longitudinal waves created by vibrating sources. Medium is needed to transmit sound waves such as air.
- wave energy travels in same direction as particles within the wave
-higher amplitude= louder
-higher frequency= high pitch

Question 23

ULTRAsound

Answer 23

Higher frequency than humans can hear

Question 24

INFRAsound

Answer 24

Lower frequency than humans can hear

Question 25

Human hearing range

Answer 25

20Hz-20 000Hz