PHYSICS ORDINARY LEVEL

Transcription

1 PRE-LEAVING CERTIFICATE EXAMINATION, 2010 PHYSICS ORDINARY LEVEL TIME: 3 HOURS Answer three questions from section A and five questions from section B. Page 1 of 9

2 SECTION A (120 marks) Answer three questions from this section. Each question carries 40 marks. 1. A student carried out an experiment to measure the velocity of an object at various times. The table shows the measurements recorded by the student. Velocity / ms Time / s (i) Draw a labelled diagram of the apparatus used in the experiment. (9) (ii) Describe how the student measured the velocity. (9) (iii) Plot a graph, on graph paper, of velocity against time. (12) (iv) From the graph, find the acceleration of the body. (10) 2. In an experiment to measure the focal length of a concave mirror, an approximate value for the focal length was found first. An object was then placed at various positions, greater than the approximate focal length, in front of the mirror. The following results were obtained: Object distance u/cm Image distance r/cm (i) Why was the object placed at a distance greater than the approximate focal length from the mirror? (4) (ii) Draw a labelled diagram to show how the apparatus might have been arranged in this experiment. Indicate the distances u and v. (12) (iii) Using the formula f = u + or otherwise, find an average value for the focal v length of the mirror. (15) (iv) Give one difference between a real image and a virtual image. (6) (v) What is meant by no-parallax between the object and the image. (3) Page 2 of 9

3 3. In an experiment to measure the specific latent heat of fusion of ice, a student wrote the following: Prepare the ice. Take the measurements. Add the ice to the water in the copper calorimeter. When all the ice has melted, take more measurements. Calculate the specific latent heat of fusion of ice. (i) Draw a labelled diagram of the apparatus. (9) (ii) How might the ice be prepared before it was added to the water? (6) (iii) What measurements should be taken before adding the ice to the water? (9) (iv) How did the student find the mass of ice? (9) (v) Give two precautions to ensure an accurate result in this experiment. (7) 4. A student wished to investigate how the resistance of a thermistor varied with temperature. (i) Draw a labelled diagram of the apparatus used. (12) (ii) The thermistor is not heated in water. Why? Name a more suitable liquid and explain why it is used. (9) (iii) How did the student measure the resistance of the thermistor? (3) (iv) The following table shows the values recorded for the resistance and the temperature during the experiment: Temperature / o C Resistance / Ω Using the data in the table, draw a graph on graph paper of the resistance against the temperature. (12) (v) Use the graph to estimate the temperature of the thermistor when its resistance is 8 Ω. (4) Page 3 of 9

4 SECTION B (280 marks) Answer five questions from this section. Each question carries 56 marks. 5. Answer any eight of the following parts (a), (b), (c), etc. (a) Give an example of a scalar and an example of a vector. (7) (b) The carriage of a hot-air balloon has an area of 2.5m 2. It weighs 300N when it rests on the ground. Calculate the pressure exerted by the carriage on the ground. (7) (c) Define specific heat capacity. (7) (d) State one difference between light waves and sound waves. (7) (e) What is noise? (7) (f) Give a use of capacitors. (7) (g) What is a transformer used for? (7) (h) What is the refractive index for (i) air and (ii) glass? (7) (i) Draw the symbol for a diode. How does it work? (7) (j) What is nuclear fission? (7) Page 4 of 9

5 6. State Newton s Universal Law of Gravitation. (9) (i) The acceleration due to gravity at the surface of the earth is given by g = GM/r 2. What is meant by the term acceleration due to gravity? (6) (ii) What do the letters M and r represent in the equation? (6) (iii) (iv) Why is the acceleration due to gravity on the moon less than the acceleration due to gravity on the earth? (5) An object of mass 0.5kg is dropped from a height 15 metres above the ground. If the object is initially at rest, calculate: (a) the time which the object will take to reach the ground. (12) (b) the velocity of the object before it hits the ground. (9) (c) the kinetic energy of the object before it hits the ground. (6) (v) In reality why is the kinetic energy less than the (initial) potential energy? (3) (Take g = 9.8ms 2 ) 7. (i) Explain what is meant by the refraction of light and give one example. (9) (ii) Describe an experiment to measure the refractive index of a liquid or a solid. (15) (iii) With the aid of a labelled diagram, explain the concept of critical angle. (6) (iv) If the critical angle for glass is 41.8 o, calculate a value for its refractive index. (6) (v) (vi) What happens when the angle of incidence exceeds the critical angle? Draw a diagram to explain your answer. (10) When light strikes a plane mirror, it becomes reflected. Give three properties of an image formed in a plane mirror. (10) Page 5 of 9

6 8. (i) Name two liquids commonly used in thermometers. (6) (ii) Give one reason why water is not a suitable liquid in thermometers. (5) (iii) (iv) To establish a temperature scale, a thermometric property is needed. What is a thermometric property? Give two examples of a thermometric property. (12) The length of a column of liquid in a uniform glass tube is 2.0cm at the freezing point of water and 27.0cm at the boiling point of water. What will the temperature be when the length of the column is 16.0cm? Give your answer in Kelvins. (12) (v) There are three types of heat transfer. Name them. (9) (vi) What is meant by the U-value of a material? (6) (vii) If a structure has a low U-value, what does this mean for its insulating ability? (6) 9. (i) What is an electric current? Give its unit. (8) (ii) (iii) (iv) If too much current flows in a plug, it could damage the appliance beyond repair and/ or cause electrocution. What safety feature is in the plug to prevent this happening? How does it work? (9) A kettle has a power rating of 2.5kW when connected to the ESB mains voltage of 230V. Calculate the current that flows in the kettle. (9) An electric current has a heating effect. Name two other effects of the electric current. (12) (v) What is meant by resistance? (6) (vi) The circuit diagram in Fig. 1 shows a 50Ω resistor and a bulb connected in series with a 6V battery. At a certain temperature, the resistance of the bulb is 100Ω. 50Ω Ω 100Ω Calculate: (i) The total resistance of the circuit. (ii) The current flowing in the circuit. 6V (12) Fig. 1 Page 6 of 9

7 10. (i) Name the sub-atomic particles in an atom. (9) (ii) Explain the terms: (i) atomic number (ii) mass number (iii) isotopes. (12) (iii) Name the three types of radiation that may be emitted by radioactive nuclei. (9) (iv) State which type of radiation is the most ionising and which is the most penetrating. (6) (v) State a material that could be used to stop the most penetrating radiation. (4) (vi) A certain isotope has a half-life of 300 days. Explain the underlined term. (6) (vii) Describe the equipment needed to measure the half-life of an isotope in the laboratory. (10) Page 7 of 9

8 11. Read this passage and answer the questions below The history of science has many examples of accidental discoveries, and the discovery of X-rays is a prime example. In England at the end of the nineteenth century, cathode rays were considered to be particles but German scientists favoured there being some kind of radiation. In 1895, the German scientist Wilhelm Röntgen ( ) was working with a cathode ray tube when he noticed an unexpected glow about two metres away from the tube coming from some barium platinocyanide, a fluorescent material that was often used to detect cathode rays. The effect could not have been caused by the cathode rays as it was known that they have a range in air of only a few centimeters. Röntgen believed that there had to be some different kind of radiation involved. Further investigations showed that this radiation could pass through human flesh but not through bones. He produced a photograph showing the bones of the hand of his wife. Not yet knowing what kind of rays they were, he called them X-rays. Subsequent work showed them to be electromagnetic waves, with wavelengths in the region of 10 8 to m. ( Physics Today by Randal Henly pg 339) (i) Give two properties of electrons. (7) (ii) How are X-rays produced? (7) (iii) Why does the target in an X-ray tube get very hot? (7) (iv) What material is used in the target of the X-ray tube. Why? (7) (v) Give two uses of X-rays. (7) (vi) Name a material that can stop X-rays. (7) (vii) Calculate the energy of an electron accelerated across a tube of potential 50kV. (7) (viii) What is the final speed of the electron? (7) e = C m = kg Page 8 of 9

9 12. Answer any two of the following parts (a), (b), (c), (d). (a) Define: (i) work (ii) power. (12) A 15kW crane lifts a mass of 1000kg through a vertical height of 5 metres in 10 seconds. Calculate: (i) the workdone (6) (ii) the average power developed (take g = 9.8ms 2 ). (6) Give one reason why the crane would not be 100% efficient. (4) (b) What is meant by resonance? (6) What is the relationship between the natural frequency of a string and its length? (6) Name two factors, in addition to length, on which the natural frequency depends. (6) Give two characteristics of a musical note. (6) Why does the same note played in different instruments sound different? (4) (c) What is meant by electromagnetic induction? (9) State Faraday s law of electromagnetic induction. (9) Explain how you would use the apparatus shown in Fig. 2 to demonstrate Faraday s N S law of electromagnetic induction. (10) Fig. 2 (d) What is a semi-conductor? (6) What are the two types of charge carriers in semi-conductors? (6) What is meant by the term doping? (6) Explain the difference between n-type and p-type semi-conductors. (10) Page 9 of 9

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