Specification reference Checklist questions

d Determine by calculation whether any more orders could be observed at the wavelength calculated in part c.
(2 marks)

From AQA Physics A PHYA2 Mechanics, Materials and Waves June 2014 (Question 6)

4. 
   Figure 4 should a ray of light incident on an optical fibre at an angle of θ₁ and meeting the inner surface of the cladding at the critical angle, θ_c.
   

Figure 4
a i Calculate the refractive index of the cladding.
critical angle, θ_c = 75.3°
refractive index of core = 1.52

refractive index of cladding

(2 marks)
a ii Calculate the angle θ₁ at which a ray can enter the optical fibre from the air and meet the core–cladding boundary at the critical angle as shown in Figure 4.
refractive index of air = 1.00
angle degree
(3 marks)
b An engineer proposes to use another optical fibre with an identical core to the optical fibre in part a but with a cladding that has a refractive index closer to, but still less than, the refractive index of the core.
State and explain how the values of the critical angle θ_c and the angle θ₁ for the optical fibre proposed by the engineer would compare to the values of θ_c and θ₁ for the optical fibre in part a.
θ_c


θ₁

(2 marks)

From AQA Physics B PHYB1 Harmony and Structure in the Universe January 2013 (Question 8)

5. 
   In an experiment, a laser is used with a diffraction grating of known number of lines per mm to measure the wavelength of the laser light.