MESH INTERNATIONAL – WAVES & QUANTUM (ALP AS) CT: 1. When a metal plate is illuminated with electromagnetic radiation of wavelength 1.5 × 10 -7 m, the maximum kinetic energy of the emitted photoelectrons is 1.2 × 10-19 J. (a) State what is meant by the work function of the metal. .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) (b) (i) Show that the work function of the metal is 1.2 × 10-18 J. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) (ii) Calculate the threshold frequency for the metal. .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) (c) The wavelength of the incident electromagnetic radiation remains at 1.50 ×10-7 m but its intensity is doubled. State and explain what changes occur, if any, to the maximum kinetic energy of each photoelectron and to the number emitted per second. You may be awarded additional marks for the quality of written communication in your answer. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(4) SHK Page 1 MESH INTERNATIONAL – WAVES & QUANTUM (ALP AS) CT: 2. The diagram shows five electron energy levels of an isolated atom. The ground state and the ionisation level are included. (a) (i) Explain what is meant by ionisation. .................................................................................................................................................................... ................................................................................................................................................................(2) (ii) Ionisation may be caused by electron impact. Explain how else might an atom be ionised. .................................................................................................................................................................... ................................................................................................................................................................(1) (iii) Calculate the ground state energy in eV. .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) (b) (i) An electron with kinetic energy 2.6 × 10-18 J collides inelastically with an electron in the ground state. State which energy levels may be occupied following this collision. ................................................................................................................................................................(1) SHK Page 2 MESH INTERNATIONAL – WAVES & QUANTUM (ALP AS) CT: (ii) A photon of energy 2.6 × 10-18 J is incident on an electron in the ground state. State and explain what would happen. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) (c) After a separate excitation process, level D is occupied. Calculate the longest possible wavelength of electromagnetic radiation emitted as the atom deexcites. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(3) 3. (a) (i) State two conditions which have to be satisfied for the formation of a stationary wave. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(3) (ii) When a stationary wave is formed on a string that is stretched between two fixed points, what additional condition concerning the length of the string must be satisfied? .................................................................................................................................................................... ................................................................................................................................................................(1) (b) Figure 3 shows the undisturbed position of a string stretched between the two points, P and Q, which are 3.6 m apart. The string is vibrated transversely at a frequency of 30 Hz, causing waves to travel along it at a speed of 72 ms-1. SHK Page 3 MESH INTERNATIONAL – WAVES & QUANTUM (ALP AS) CT: Figure 3 (i) Calculate the wavelength of the waves on the string. .................................................................................................................................................................... ................................................................................................................................................................(2) (ii) Draw on Figure 3 the appearance of the stationary wave formed under these conditions. (2) (iii) Compare the vibrations of the mid-point R of the string with those of point S, which is 0.6 m from Q, with reference to amplitude, frequency and phase. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(3) 4. (a) Distinguish between the nodes and antinodes that can be seen when stationary waves are formed on a vibrating string. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) SHK Page 4 MESH INTERNATIONAL – WAVES & QUANTUM (ALP AS) CT: (b) Figure 4 Figure 4 shows two dippers, D and E, mounted on the same vibrating beam. The dippers touch the surface of the shallow water in a ripple tank. When the beam vibrates, waves travel outwards in all directions on the surface of the water from each dipper. Explain why a stationary wave will be formed on the surface of the water along the line joining D and E. You may be awarded additional marks to those shown in brackets for the quality of written communication in your answer. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(4) (c) When the beam vibrates at a certain frequency, the distance between two adjacent nodes along the line between D and E is 12 mm. When the frequency of vibration is increased by 2.0 Hz, the distance between two adjacent nodes is decreased to 10mm. Calculate (i) the frequency at which the beam vibrated originally, .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) SHK Page 5 MESH INTERNATIONAL – WAVES & QUANTUM (ALP AS) CT: (ii) the speed at which the waves travelled on the surface of the water. .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) 5. (a) Two identical loudspeakers, S1 and S2, are connected to the same signal generator so that each produces a sound wave of frequency 850 Hz. They are arranged in the open air, as shown in Figure 5, with their centres 3.2 m apart. An observer who walks along the line LM, 16 m away from the loudspeakers, notices that there are minima of sound every 2.0 m. Figure 5 Calculate (i) the wavelength of the sound waves, .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) (ii) the speed of sound in the air. .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(2) (i) The sound waves from the loudspeakers in part (a) produce interference effects. Light waves from two separate small monochromatic light sources of the same frequency do not produce observable interference effects. SHK Page 6 MESH INTERNATIONAL – WAVES & QUANTUM (ALP AS) CT: Explain why the loudspeakers are able to produce interference effects but the light sources do not. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(3) (ii) Describe and explain how interference effects may be produced from a single monochromatic light source using appropriate additional equipment. You may draw a diagram to illustrate your answer. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ................................................................................................................................................................(6) SHK TOTAL FOR THIS PAPER: 55 MARKS Page 7
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