Physics
PART B
40 Marks
TRIAL A FINAL
PART B Question and Answer Booklet
Question 1 [6 Marks]
A mixture of red and blue light is incident on a glass prism ABC as shown. The diagram also shows the emerging rays.
(a) Explain which ray (Ray 1 or Ray 2) is red light.
(b) Find the refractive indexof this glass for Ray 2.
(c) Calculate the angle between Ray 2 (as it emerges into the air) and the face BC.
Question 2
An electron travelling at 5.0 × 106 ms-1 in a vacuum enters at right field of flux-density 2.4 mT as shown:
(a) Calculate the magnitude of the magnetic force on the electron as it moves along the path from A to B.
(b) Explain why the electron moves in a circular path while it is in the field.
(c) Calculate the radius of this path.
Question 3 [8 Marks]
A converging lens of focal length 200 mm isplaced 300 mm to the right of a concave mirror of radius 800 mm as shown. A small object is placed 200 mm to the right of the lens.
(a) What is the focal length of the mirror?
(b) Where (if anywhere) is the image formed by the lens alone?
(c) Where (if anywhere) is the image formed by the mirror from rays that have already passed through the lens?
(d) Where (if anywhere) is the final image?
Question 4 [ 10 Marks]
An organ-pipe a, closed at one end and open at the other, is 3.43 m long. The end-correction maybe ignored. Take the speed of sound to be 343 m s-1.
(a) Find the fundamental frequency of this pipe.
(b) Draw a diagram to show the vibrational pattern in the pipe in its second overtone.
(c) Find the frequency of its second overtone.
Pipe B is open at both ends and has a fundamental frequency which is the same as the second overtone of Pipe A.
(d) Find the length of Pipe B.
(e) What is the next highest frequency at which Pipes A and B can both resonate?
Question 5 [10 Marks]
A diffraction grating has 105 lines per millimetre. Abeam of coherent red light of wavelength 633 nm (6.33 × 10-7 m ) is incident normally to the grating. The distance between the two first- order bright fringes on a distant screen is measured to be 1.12 m.
(a) Calculate the distance between two adjacent lines on the grating.
(b) Calculate the distance between the grating and the screen.
(c) Calculate the maximum number of constructive interference-fringes which it is possible to form. with this diffraction grating and light source.
(d) (i) If the red light were replaced with blue light of wavelength 440 nm,
would the distance between adjacent bright fringes on the screen increase, decrease or stay the same?
(ii) Explain your answer.