unit 3 - waves

Question 1

Waves

Answer 1

disturbances created in a medium which transfers energy and momentum from one point to another, cant tranfer matter

Question 2

Propogate

Answer 2

To travel

Question 3

In waves, what do particles do>

Answer 3

They dont move, they just oscillate and vibrate , tranansferring the wave from one particle to another, and sometimes get reflected

Question 4

what happens to medium in waves

Answer 4

remains static

Question 5

Types of waves based on requirement of meidum to travel

Answer 5

Electromagnetic and Mechnical waves

Question 6

Electromagnetic waves

Answer 6

Waves which do not require a medium to propoagte. Wave in which the electrical field and the magnetic field mutually oscillate perpendicular to the propagation of the wave\

Eg = Light waves

Question 7

Mechanical waves

Answer 7

Waves which require medium to travel

eg = Sound waves, water ripples, seismic waves

Question 8

Types of waves based on movement of particles

Answer 8

Transverse and Longitudinal

Question 9

Transverse waves

Answer 9

Propogation of particle is perpendicular to the direction of propogation of energy, particles oscillate up and down

eg = em waves and light waves

Question 10

Longitudanal Waves

Answer 10

1. Vibration of particles in the medium is parallel to the direction of propagation of wave

It looks likes particles are moving left to right but they come back to their mean position

Eg - sound waves, waves produced in a slinky

Question 11

Compression

Answer 11

Area in longitudnal waves where the particles are close to each other, the area where density and pressure are higher than normal

Question 12

Rarefaction

Answer 12

Area in a longitudnal wave where the particle are far apart from each other, the area where density and pressure are less than normal

Question 13

4 characterstic properties of waves

Answer 13

1. wavelength
2. amplitude
3. frequency
4. Wave velocity

Question 14

Wavelength (transverse)

Answer 14

Distance between two consecutive troughs or crests

Si unit = mtr

Symbol = Lambda

Question 15

wavelength (longitudanal)

Answer 15

measure distance between 2 consecutie compressions or rarefaction

Question 16

Amplitude

Answer 16

Maximum displacement of a particle from its mean position in the positive or negative direction

si unit = mtr

symbol = A

Question 17

Frequency

Answer 17

• No. of disturbances/waves per unit time
• No. of oscillations per unit time
• Si unit = Hertz (Hz)
• 1 Hz = 1 wave per second
• To calculate frequency, we can also count the number of waves (from crest to crest or trough to trough) in a one second diagram

Question 18

Wave velocity

Answer 18

• distance a wave travels per unit of time
• Also known as Phase velocity
• Symbol = V
• Si unit = ms^-1
  formula = lambda times frequency

Question 19

Time period

Answer 19

Time taken to complete one full oscillation
Si unit = sec
formula = T = 1/f

Question 20

Wave equation

Answer 20

Speed = Freuqney times wavelength
Frequency = speed/wavelength
Wavelength = speed/frequency

Question 21

Wave phenomenons

Answer 21

1. Reflection
2. Refraction
   
   1. Total internal reflection
3. Dispersion
4. Diffraction

Question 22

Ray

Answer 22

direction in which a wave propogates

Question 23

reflection

Answer 23

A phenomenon in which a wave bounces back into the same medium after being incident on a reflection surface

Question 24

laws of relfection

Answer 24

1. The incident ray, the reflection ray and the normal to the reflecting surface must lie on the same plane
2. The angle of incidence all lie on the same plane

Question 25

point of inciencde

Answer 25

The point on a surface at which the incident ray hits/strikes and causes phenomenon like reflection and refraction

Question 26

Refraction

Answer 26

• For refraction, the wave must travel must rarer to denser medium

Change in speed of a wave when passing from one medium to another

• Change in direction of motion
• Frequency does not change!
• Angel of incidence increases = Angle of refraction also increase

Question 27

bending of refracting ray - denser to rarer

Answer 27

Away from normal

Question 28

Bending of refracting rray - rarer to denser

Answer 28

towards the normal

Question 29

Laws of refraction

Answer 29

1. The incident ray, the refracting ray and the normal to the surface or separation at the point of incidence must lie on the same plane
2. Snells Law: The ratio of sine of angle of incidence and the sine of angle of refraction for a given pair of media is always constant and is called the refractive index of the second medium with respect to the first medium

Question 30

formula for snells law

Answer 30

sin i/ sin r = n1/n2 = v2/v1

Question 31

Total internal reflection

Answer 31

• when a wave propogates from a denser to rarer medium, TIR (total internal reflection) takes place
• Speed increase in TIR
• Refracted ray bends away from normal
• In TIR, 100% of the wave is reflected

Question 32

conditions for total internal relfection

Answer 32

1. Incident ray must travel from rarer to denser medium
2. ∠i must be greater than the critical angle

Question 33

critical angle

Answer 33

Angle of incidence for which the corresponding angle of refraction is 90°

Question 34

diffraction

Answer 34

Phenomenon in which a wave spreads whenever it comes across an obstacle or a slit, provided the size of the slit or the obstacle in comparable to the wavelength of the wave

Question 35

dispersion

Answer 35

• Phenomenon in which a polychromatic light splits into its monochromatic constituents

Higher the wavelength, lesser the deviation

eg = white light splitting into vibgyor colour

Question 36

basic cause of dispersion

Answer 36

refraction multiple times

Question 37

Sound waves

Answer 37

Longitudanal waves
produced by vibrations
Require medium to transfer energy
Cant travel through vaccum

Question 38

reflection of sound

Answer 38

echo