EM waves + waves

Question 1

EM spec from highest to lowest frequency

Answer 1

Gamma (violet)
X ray
UV- flourscent lamps//dmage to skin cells
Visible light- optical fibers + photography
Infared- heaters/night vision + skin burns
Microwave- cooking/satelite transmissions + internal heating of BT
Radio- communications,comms (red)

Question 2

whats a transverse wave

Answer 2

• wave with oscillations that is perpendicular to waves direction (90º)
• e.g EM waves

Question 3

what are the uses and cons to useing gamma rays

Answer 3

• sterllise medical equipment and food
• used in cancer diagnosis
• can lead to mutations/damage body cells
  leading to death

Question 4

At what speed does an EM wave travel in a vacum

Answer 4

3x10 (power of 8) m/s

Question 5

does the danger of EM increase with wavelength or frequency

Answer 5

with frequency

Question 6

4 properties of EM waves

Answer 6

• all transverse
• all transfer energy & info
• travel at speed of light in vacum
• can be reflected/retracted/diffracted

Question 7

whats the doppler effect

Answer 7

• when wave source moves toward observer

frequency increases wavelength decreases vice versa

Question 8

Mneumonic for EM spec

Answer 8

Rotten - Radio
Men - Micro
Inevitably - Infrared
visit - Visible light
ugly- UV
x - X-rays
girlfriends - Gamma

Question 9

sound + doppler

Answer 9

• longitudinal waves
• can be refracted + reflected
• travels fast in solids due to close packing of particles
• wave source is moving relatively to observer= change in frequency + wavelength

Question 10

how to meaure speed of sound in ai

Answer 10

1. make a lound echo/gun
2. large dist from a solid wall
3. read time for echo to be heard
4. then use s=d/t (distance=2x)

Question 11

light waves + law of reflection





Answer 11

• angel of incidence = angle of refraction

- The angle found between the ray + normal

Question 12

oscilliscop and waves

Answer 12

• the lower the sound = greater amplitude

- the higher the frequency= higher its pitch

Question 13

longitudinal waves

Answer 13

• consists of compressions and rarefactions
• vibrations are in parallel/same direction of travel
• e.g sound

Question 14

optical fibers

Answer 14

• thin rod of glass using TIR to tranfer light, despite bent
• used in wifi
• visible light

Question 15

define these terms:
amplitude
wavelength
periods
frequency

Answer 15

• max distance from the normal
• distance between 2 peaks or trough
• time taken to produce one wave
• number of waves past a single point per s

Question 16

total internal reflection + refractive index of glass

 

Answer 16

• occurs when the angle of incidence > critical angle
• ray travels from high to low refractive index
• refractive index of glass is 1.5

Question 17

refraction + how density of medium affects refractive index



Answer 17

• bending of light due to change in speed through each medium
• more dense= light bends towards normal + speed decreases
• less dense- light bends away from normal + speed increases

Question 18

which color has highest frequency and highest wavelength + lowest frequency and lowest wavelnegth

Answer 18

• violet

- red

Question 19

what do EM waves transfer

Answer 19

energy & information

Question 20

what happens when a light is refelcted off a boundary

Answer 20

its reflected (bounced) off a smooth flat surface
angle of incidence is the same as angle of reflection

Question 21

Describe an experiment to determine the refractive index of a glass block.

Answer 21

• use light/torch
• ruler/pencil
• protractor
• measure angle of incidence + refraction
• repeat for diff angles
• use equation to calc