waves

Question 1

wave speed equation

Answer 1

frequency x wavelength

Question 2

a method to measure speed of sound waves in air?

Answer 2

• make two people stand at a distance
• let one hold a timer and one hold cymbals
• person 1 starts the timer when person 2 clashes the cymbals and stops it when they stop hearing the echo of it
• calculate speed by distance divided by time

Question 3

problems with the speed of sound in air experiment

Answer 3

-takes time to start timer
-you can solve this problem by trying with lots of observers and calculating mean

-its very hard to start and stop between a short distance
-you can solve by using a long distance

Question 4

ripple tank experiment

Answer 4

-take a ripple tank
-when lamp light shines on water, it will create an image on the paper
-freeze the image and use ruler to measure wavelength
-then place timer next to paper
-count how many waves pass in one second (frequency)
-use wavelength x frequency to find out wave speed

Question 5

waves in a solid experiment

Answer 5

• turn on apparatus and let it vibrate untill u see standing wave (caused by resonance)
• measure length of it and read frequency on powerpack
  -frequency x wavelength is wavespeed

Question 6

Angles of incident, reflection and refraction

Answer 6

incident and reflection angle dosent change based on the material but refraction angle does

Question 7

how do we hear with sound waves?

Answer 7

-sound waves in the air hit the eardrum
-this causes eardrum to vibrate
-causes sound

Question 8

human hearing range

Answer 8

20-20,000hz

Question 9

what is ultrasound

Answer 9

sound wave with frequency higher than normal hearing range

Question 10

structure of earth

Answer 10

crust,mantle and inner core are solid. The outer-core is liquid

Question 11

How does earthquakes show seismic waves

Answer 11

-earthquake causes tectonic plates of earth to move
- this causes seismic waves

Question 12

P waves and S waves

Answer 12

-P waves are longitudinal waves passing through liquids and solids
- S waves are transverse waves passing through solids only

Question 13

Electromagnetic waves

Answer 13

transverse waves that transfer energy from the source to the absorber.

Question 14

electromagnetic spectrum colour

Answer 14

red= low frequency long wavelength
purple= high frequency short wavelngth

Question 15

electromagnetic spectrum

Answer 15

raw meat is very ugly except giraffes
Radio, microwaves, infrared , visible light, ultraviolet, x rays, gamma rays

Question 16

how do waves refract

Answer 16

-when ray of light enters glass block, the wave slows down and bends towards normal
- when it leaves the glass block, it speeds up and bends away from normal

Question 17

infrared practical

Answer 17

-take leslie’s cube with four materials (shows how much is absorbed)
-fill it with water
- point infrared detector to each surface
-shows infrared emission

Question 18

How to measure absorbance of infrared

Answer 18

take two metal plates with different materials and put infrared heater in the middle. Put a pin with vaseline on both plates and whatever falls first absorbs more.

Question 19

what happens when electromagnetic waves are absorbed

Answer 19

when atoms r heated then it changes to one higher energy level. when it returns to its normal
place, it emits light.

Question 20

hazards of the high end waves

Answer 20

ultraviolet waves cause skin cancer
x rays and gamma rays ionise radiation which causes mutations to genes.

Question 21

Radio waves

Answer 21

radio waves can travel long distances whixh allows us to be in contact with people across the earth

Question 22

microwaves

Answer 22

food with water molecules absorb the energy making it hot

Question 23

infrared

Answer 23

energy of it is easily absorbed by objects making the room warm (heater)

Question 24

ultraviolet

Answer 24

found in lightbulbs and its short wavelngth allows it to carry a lot of energy