Question 6a)Awould-be telescope maker discover two lenses in a box at the back of the lab. One is a convex meniscus lens with front radius of curvature r1= 22.4 cm and a back radius of curvature r2= 46.2 cm. The other is a plano-convex lens with one flat surface and one surface with a radius of curvature of 2.4 cm. (i)What are the focal lengths of the two lenses, if they are both made from a glass with index of refraction n = 1.60? [2 marks](ii)Which one of the lenses has the higher power? [2 marks](iii)Which lens should be used as the objective and which as the eyepiece if a useful telescope is to be made (if necessary, you may assume that they are the same diameter). [1 mark](iv) What is the angular magnification of an image formed by the lenses arranged in this way? [1 mark]b) Briefly describe the meaning and significance of the following optical concepts, using clearly labelled diagrams where it would assist your explanation: (i)Total internal reflection.
[2 marks]
(ii)A virtual image. [2 marks]c) A candle of height his 24.0 cm to the left of a converging lens with a focal length of 12.0 cm. A converging lens with a focal length of 10.0 cm is 36.0 cm to the right of the first lens. (i) Draw a ray diagram of the situation, showing just those rays necessary to locate the final image starting from the tip of the candle. Make sure all relevant distances and locations are clearly labelled. [2 marks](ii) Calculate the position of the image formed by the first lens.
[2 marks]
(iii) Calculate the lateral magnification of the first image. Is it real or virtual? [2 marks](iv) Calculate the position of the image formed by the second lens. [2 marks](v) Calculate the lateral magnification of the final image (compared to the candle). Is the final image real or virtual?
[2 marks]
Continued…

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KYA102 Physics 1B, Paper 1
8
Question 7 a)In a photoelectric effect experiment, the metal cathode was illuminated with ultraviolet radiation at four different frequencies, and the stopping potential V0was measured for each frequency, recorded in the following table: (i) Sketch the graph of νagainst V0. Write down the equation of a line through the data of the form y = mx+b, and explain the physical meaning of the coefficients in terms of the theory of the photoelectric effect. [2 marks] (ii) From the graph or otherwise, make a calculation of the work function for the metal, expressed in electron-volts (eV). [2 marks] (iii) Based on your work above, make a calculation of the value of Planck’s constant hin eV·s. You must show your work to receive credit. [2 marks]b) The Heisenberg uncertainty principle is a fundamental result of quantum mechanics that has profound implications for the behaviour of matter on atomic and subatomic scales.(i) Carefully explain what is meant by the Heisenberg uncertainty principle. [2 marks](ii) Give examples of two pairs of variables affected by the principle.
[2 marks]

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