SP4 Physics

Question 1

What is a wave

Answer 1

a process of transfering energy from a region of high energy to a region of low energy

Question 2

Amplitude definition and unit

Answer 2

greatest distance a particle is displaced from its normal resting position

meters

Question 3

Wavelength definition and unit

Answer 3

wavelength is the distance between two successive identical points on a crest

meters

often seen as λ

Question 4

Period(T) definition and unit and formula

Answer 4

Time required for one full wave to pass a certain point

Seconds

T=1/F

Question 5

frequency definition and unit

Answer 5

is the number of waves that pass a point in 1 second

Hertz (Hz)

Question 6

Describe Transverse Wave and Compression/Longitudinal Waves

Answer 6

Transverse Wave:
the waves vibrate perpendicular to the direction of the waves motion

Longitudinal Wave:
the vibration of waves that are parrellel to the direction of propgation of the wave

Question 7

define compression and trough

Answer 7

Compression is the region of high pressure in a longitudinal wave
while trough is the region of low pressure in a longitudinal wave

Question 8

describe crest and trough

Answer 8

crest is the highest point in a transverse wave
trough is rhe lowest point in a transverse wave

Question 9

Mechanical waves vs Electromagnetic waves

Answer 9

Mechanical waves are the oscillation of particles in a physical medium. They cannoy transmit energy in vacuum
Can be transverse or longitudinal
- Soundwaves, P&S waves or waterwaves

Electromagnetic waves are produced by the acceleration of charged particles. Can transmit energy through a vacuum. Always transverse
- Light, X-ray, gamma ray, ultraviolet

Question 10

How to calculate speed
Both Normal and Echo version

Answer 10

NORMAL:
s= d/t

ECHO VER
s= (2d)/t

Question 11

Experiment to determine speed of sound

Answer 11

Requires:
- Stopwatch to record time
- Measuring tape to measure distance
- Source of a sound(bell)
-flag to signal to the other person

1. one student stands at the starting position with a bell and source o sound. at the other end another stands with a stopwatch
2. Stufent at the start raises his flag as he is about to hit the bell
3. Once person B sees the flag up he starts the stopwatch, once he hears the bell he stops the stopwatch.
4. Repeat several times to gain an accurate result

Question 12

Waves speed moves faster in solids bc?
(mostly in longitudinal waves)

Answer 12

Particles are closer together
energy transfer takes place as sound is longitudinal

Question 13

What is pitch and loudness related to?

Answer 13

Higher frequency means higher pitch
Higher amplitude of sound then higher louder the sound

Question 14

What waves can do?

Answer 14

Can be
1. Reflected
2. Refracted
3. Transmitted
4. Absorbed

Question 15

What is reflection and Refraction?

Answer 15

Reflection:
When light falls on a highly polished surface like a mirror most of the light id sent back into the same medium. This process is called reflection of light.
During reflection
- direction changes
- speed, frequency and wavelength are not changed

Refraction:
Is the change in direction of a wave as it passes from one medium to another medium

Question 16

Describd Specular and Diffuse Reflection

Answer 16

Specular Reflection:
- Occurs at the surface of a plane like a plane mirror. Reflected rays after regular reflection are parrallel

Diffuse Reflection:
- Occurs at the surface of a rough surface like cardboard. Reflected rays after regular reflection are
not parrallel

Question 17

Properties of an image by a mirror

Answer 17

Laterally inverted
same size as the object
virtual

Question 18

how to calculate frequency

Answer 18

V= fλ

f= V/λ

Question 19

Describe Real depth and apparrent depth

Answer 19

real depth is the actual depth or position of the object underwater

apparent depth is the depth/position percieved by an observer due to the refraction of light

Question 20

Describe water fronts in shallow and deep water

Answer 20

In shallow water speed decreases(is slower) and is closer to the normal, and wavelength decreases

In deepwater speed increases and moves away from the normal, longer wavelength

waterwave speed increases with depth

Question 21

Explain how ears detect sound

Answer 21

1. Soundwaves enter the ear canal
2. the eardrum is a thin membrane. soundwaves make it vibrate
3. vibrations are passed on to tiny bones which amplify the vibrations
4. vibrations are passed on to the liquid inside the cochlea
5. tiny hairs inside the cochlea detect these vibrations and create signals called impulses
6. impulses travel along neurons in the auditory nerves to reach the brain

Question 22

how cochlea works?

Answer 22

Cochlea is a coiled tube containing a liquid. it can detect different frequencies, in a human from 20Hz to 20,000 Hz

the base of the cochlea can detect high frequencies(20,000Hz) and the apex can detect low frequencies(200Hz)

Question 23

What is ultrasound and what is infrasound

Answer 23

Ultrasound:
-Sound with a higher frequency than 20,000 Hz that cannot be heard by humans

Infrasound;
- Sound with a lower frequency than 20Hz that is too low for us to hear

Question 24

Uses of ultrasound

Answer 24

Medical uses (fetal scanning, diagnosis, treatment)
SONAR (Sound Navigating And Ranging)

Question 25

How ultrasound can be used to find faults in manufactured items

Answer 25

• The machine is passed over the object being tested. If there are no cracks, it will detect just one echo from the farside of the object.

-If there is a crack it will detect an echo from the crack as well. the timing of this echo can be used to work out how deep into the material the crack is located

Question 26

Infrasound expanded

Answer 26

Less than 20 Hz too low too be heard by humans.

Can travel further than higher frequencies

Seismic waves are a type of infrasound

Question 27

define primary and secondary waves

Answer 27

P-Waves:
- Longitudinal waves that can travel through solids and liquids
-Faster than S waves

S-Waves:
-Transverse waves that can travel through solids
- slower than p-waves

Question 28

Uses of Seismic waves

Answer 28

• to prove facts about the interior or the earth
• to locate the epicenter of earthquarkes.
• used to detect oil

Question 29

why are p waves and swaves curved?

Answer 29

Curve because the property of the rocks in the mantel change gradually with depth.
This means that the part of the sound in the mantel also changes gradually with depth