2014年11月IB物理(SL)真题PDF下载-Paper3
1. This question is about the eye and sight.
(a) Compare the functions of the rods and cones in the retina.
(b) Outline the process of accommodation of the eye.
2. This question is about standing (stationary) waves.The diagram shows a tube that is open at both ends.
Point A shows the position of one air molecule in the tube. A standing sound wave (not shown in the diagram) is set up in the tube.
The graph shows the variation of displacement s with time t for the molecule at point A.
(a) Outline whether the standing wave is transverse or longitudinal.
(b) The standing wave in the tube corresponds to the fourth harmonic. The speed of sound in the tube is 340ms–1. Using the graph, determine the length of the tube.
(c) The tube is now closed at one end and the first harmonic is sounded. Outline why the tube that is open at both ends produces a first harmonic with a wavelength shorter than the first harmonic of the tube that is closed at one end.
3. This question is about the Doppler effect.
Georgia carries out an experiment to measure the speed of mosquitoes. She sets up a microphone to record the sounds of passing mosquitoes.
One mosquito is moving in a straight line with constant speed and passes very close to the microphone as seen in the diagram. The mosquito produces a sound of constant frequency.The speed of sound in air is 340ms–1.
(a) The maximum frequency recorded is 751 Hz and the minimum frequency recorded is 749 Hz. Explain this observation.
(b) Determine the speed of the mosquito.
4. This question is about polarization.
(a) Distinguish between polarized light and unpolarized light.
(b) In a liquid-crystal display (LCD), liquid crystals are contained between two glass plates.Electrodes are etched on the glass plates.
The LCD also includes two plane polarizing sheets and a reflecting surface.
(i) Draw and label the position of the two polarizing sheets and of the reflecting surface.
(ii) The two sheets are arranged with their polarizing planes at right angles.Unpolarized incident light enters the LCD and after reflection, exits from the same side as shown in the diagram. The light has intensity I0 when incident on the LCD and intensity I when it exits the LCD.
Determine the ratio I/I0
5. This question is about the wave nature of matter.
(a) Describe wave-particle duality in relation to the de Broglie hypothesis.
(b) In 1927 Davisson and Germer tested the de Broglie hypothesis. They directed a beam of electrons onto a nickel crystal as shown in the diagram. The experiment was carried out in a vacuum.
(i) The electrons were accelerated through a potential difference of 54 V. Show that the associated de Broglie wavelength for the electrons is about 2×10–10 m.
(ii) The electron detector recorded a large number of electrons at a particular scattering angle θ . Explain why a maximum in the number of scattered electrons is observed at a particular angle.
6. This question is about atomic spectra and energy states.
(a) Outline how atomic absorption spectra provide evidence for the quantization of energy states in atoms.
(b) The diagram shows some atomic energy levels of hydrogen.
A photon of energy 2.86 eV is emitted from a hydrogen atom. Using the diagram,draw an arrow to indicate the electron transitions that results in the emission of this photon.
7. This question is about radioactive decay.
In a particular nuclear medical imaging technique, carbon-11(116C) is used. It is radioactive and decays through β+ decay to boron (B).
(a) (i) Identify the numbers and the particle to complete the decay equation.
(ii) State the nature of the β+ particle.
(b) The half-life of carbon-11 is 20.3 minutes.
(i) Outline a method for a measuring the half-life of an isotope, such as the half-life of carbon-11.
(ii) State the law of radioactive decay.
(iii) Derive the relationship between the half-life T1/2 and the decay constant λ , using the law of radioactive decay.
(iv) Calculate the number of nuclei of carbon-11 that will produce an activity of 4.2×1020 Bq.
2014年11月IB物理(SL)真题余下省略！
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