Light

Question 1

How to measure an accurate value for refractive index of a glass block

Answer 1

• use ray box and vary sin (i) for a range of results
  -use protractor
• use formula sin(i)/sin(r)
  -find gradient of graph sin(i)/sin(r)
• draw lines with ruler, use sharp pencil, fix glass block in firm position etc.

Question 2

what is critical angle?

Answer 2

name given to angle of incidence when angle of refraction is exactly 90 degrees.

Question 3

Why does diamond have more chance of TIR light than opal?

Answer 3

• Low critical angle so easier for TIR to occur
• Opal has high critical angle so light needs to enter opal at high angles to TIR
• Diamond is more optically dense and therefore has higher refractive index, and hence smaller crtical angle making it easier for light to TIR

Question 4

TIR occurs at smaller angles when?

Answer 4

critical angle is small

Question 5

Examples of longitudinal waves?

Answer 5

tsunami waves, sound, ultrasound, seismic p wave

Question 6

examples of transverse wave?

Answer 6

light, em spectrum, ripples in water

Question 7

examples of where TIR is used?

Answer 7

optical fibres e.g. endoscopes

prisms e.g. periscopes

Question 8

TIR occurs when?

Answer 8

Light goes from more dense to less dense material and angle of incidence is greater than critical angle, ALL light gets reflected back in.

Question 9

is being optically dense mean refractive index is higher or lower?

Answer 9

higher

Question 10

having higher refractive index means critical angle is low or high?

Answer 10

low

Question 11

TIR for any object occurs between which angle and 90 degrees?

Answer 11

critical angle.

eg- opal TIR between 42 and 90 degrees, and diamond between 25 and 90.
therefore diamond is sparklier and will TIR more because it has a larger range of angles at which light can TIR.