*B16* Pre-Leaving Certificate Examination, 2014 Triailscrúdú na hardteistiméireachta, 2014 PHYSICS ORDINARY LEVEL TIME: 3 HOURS Answer three questions from Section A and five questions from Section B. N.B. Relevant data are listed in the Formulae and Tables booklet, which is available from the Superintendent. Page 1 of 10
SECTION A (120 marks) Answer three questions from this section. Each question carries 40 marks. 1. The momentum of a body is given by the formula ρ = mv. (i) What does the symbol v stand for? (3) (ii) Draw a labelled diagram showing how you would verify the principle of conservation of momentum. (12) (iii) What measurements do you record during this experiment? (9) (iv) How do you get a value for v from the measurements you took? (9) (v) How would you know that the principle of conservation of momentum was verified? (7) 2. The diagram shows a circuit used by a student to investigate the variation of current with potential difference for a metallic conductor. X A Y (i) Name the parts of the apparatus labelled A, X and Y. (9) (ii) What does X measure? (3) (iii) Describe how the part labelled Y was used in the experiment. (6) The following table shows the values recorded for the current I and the potential difference V during the experiment. I / A 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 V / V 0 0. 6 1. 2 1. 7 2. 4 2. 9 3. 6 4. 3 4. 8 (iv) Using the data, draw a graph on graph paper of I against V. (12) (v) From your graph, calculate the resistance of the conductor. (Hint: V = IR) (10) Page 2 of 10
3. In an experiment to measure the speed of sound in air, a student found the frequency and the wavelength of a sound wave. (i) Draw a labelled diagram of the apparatus used in the experiment. (12) (ii) Describe how the student found the wavelength of the sound wave. (9) (iii) How did the student find the frequency of the sound wave? (6) (iv) State one difference between light waves and sound waves. (6) (v) What is an ultra sonic wave? (3) (vi) Give one precaution that the student took to get an accurate result. (4) 4. You carried out an experiment to measure the focal length of a converging lens. (i) Draw a labelled diagram of the apparatus that you used in the experiment. (12) (ii) Describe how you found the position of the image formed by the lens. (6) (iii) What measurements did you take? (9) The table shows the measurements recorded by you: U / cm 20 30 40 50 V / cm 64 43 41 35 1 1 1 (iv) Using the formula = + or otherwise and the above data, find an average value f U V for the focal length f of the lens. (13) Page 3 of 10
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) A person whose weight is 700 N enters a lift at the ground floor. The lift rises 10 m to the third floor. Calculate the work done on the person. (W = Fs) (b) Why is frost unlikely on a cloudy winter s night? (c) Convert 27 C to Kelvin. (d) What physical quantity is measured in decibels? (e) What is the colour of the live wire in an electric cable? (f) Give one use for a semiconductor diode. (g) Which atomic particle was named by the Irish scientist G. J. Stoney? (h) State two properties of x-rays. (i) Name a radioactive isotope used in finding the age of an object. (j) Give an example of the doppler effect. (8 7) Page 4 of 10
6. Copy this statement of Newton s final law of motion into your answer book and complete it: (a) An object remains at rest or moves with constant speed in a straight line unless... (9) (b) A car of mass 1200 kg was travelling at a constant speed along a level road. Draw a diagram showing two of the forces acting on the car. (8) The car hit a wall at a speed of 20 ms 1 and was stopped in 0. 2 s. 1 20 ms Wall Calculate: (i) The acceleration of the car during the collision. (9) (ii) The resultant force acting on the car during the collision. (6) (iii) The energy of the car just before it hits the wall. (6) (c) The driver was not wearing a seat belt and hit the steering wheel when the car was suddenly stopped in the collision. Explain why the driver hit the steering wheel during the collision. Refer to Newton s first law of motion in your answer. (9) (d) How could wearing a seat belt have prevented the driver hitting the steering wheel? (6) (e) Name one other safety feature in cars. (3) mv V = u+ at, F = ma, Ek = 2 2 Page 5 of 10
7. (i) What is meant by temperature? (6) (ii) Heat can be transferred by conduction. Name two other ways of transferring heat. (6) (iii) Describe an experiment to show how different solids conduct heat at different rates. (15) (iv) The spongy material in a wet-suit contains trapped air that keeps the layer of water near a swimmer s skin from moving. Explain how the trapped air can keep a swimmer warm. (6) (v) Explain how the layer of water can keep a swimmer warm. (6) (vi) A vacuum flask (thermos flask) is designed to keep a liquid at constant temperature by preventing energy entering or leaving the flask. With reference to the diagram, explain how the flask prevents energy entering or leaving the flask. (17) Stopper Vacuum Silvered walls Liquid Page 6 of 10
8. (i) Describe an experiment to show the heating effect of an electric current. (12) The diagram shows part of a lighting circuit: 230 V Fuse A B (ii) A is a 75 W lamp. Calculate the current flowing through lamp A when the switch is closed. (12) (iii) At the same time, the current flowing through the fuse is 0. 76 A. What is the current flowing through lamp B? (6) (iv) Calculate the power generated in lamp B. (9) (v) Explain how a fuse acts as a safety device in an electrical circuit. (6) (vi) An electric kettle is rated 3 kw. The kettle is switched on for 30 minutes each day. How many units of electricity does the kettle use each day? (6) (vii) How much does it cost to use the kettle each day when one unit of electricity costs 15 cent? (5) (P = VI, 1 unit = 1 kw hour) Page 7 of 10
9. (i) What is the difference between a permanent magnet and an electromagnet? (6) (ii) Magnets have many uses in the home. Give one use in the home of (a) a permanent magnet (b) an electromagnet. (6) (iii) The needle of a magnetic compass is a permanent magnet. Explain why a nearby electric current causes a compass needle to move. (9) (iv) A solenoid (long coil of wire) is connected to a cell as shown. Copy this diagram into your answer book and draw the magnetic field around the solenoid. (9) (v) Explain the term electromagnetic induction. (9) (vi) A magnet and a coil of wire can be used to produce electricity. Describe with the aid of a diagram how to show this. (17) 10. Alpha, beta and gamma (α, β, γ) are three types of radiation. Match each of the following descriptions with the correct type of radiation: (i) (ii) Short-wavelength electromagnetic radiation. A particle consisting of two protons and two neutrons. (iii) A fast moving electron. (9) Radon-222 is a radioactive gas that can seep into buildings from underground rocks. It undergoes the following nuclear reaction: Rn Po + He 222 218 4 86 84 2 (iv) What type of radiation is emitted by radon-222? (6) (v) What is a possible effect on your health caused by high levels of radon gas? (5) (vi) Explain what is meant by the half-life of a radioactive material. (6) (vii) The half-life of radon-222 is 4 days. The activity of a sample of radon-222 is measured as 520 Bq. Estimate the activity of the sample after 8 days. (9) (viii) What is the principle on which a detector of ionising radiation works? (9) (ix) Which has the most penetrating power, α, β or γ? (6) (x) How would you compare the penetrating powers of the three types of radiation? (6) Page 8 of 10
11. Read the following passage and answer the accompanying questions. Forty of every hundred workers who have worked all their lives at high noise levels (90 db) will, at the age of 65 years, fi nd it diffi cult to hear other people talking. Some of these workers will even be deaf. If you are exposed to continuous loud noise at work there are rules your employer must follow to protect you from noise exposure. They must assess, measure and control noise and supply hearing protection as appropriate. The level of noise to note is 85 db. If it is necessary to communicate by shouting at a distance of 2 m, the noise level may be greater than 85 db. Adapted from a Health and Safety Authority leafl et on noise exposure. (a) (b) (c) (d) (e) (f) (g) (h) What is noise? What must employers do if their workers are exposed to high noise levels? How might a person s hearing be affected by exposure to high noise levels? Name a job where a worker might experience a high noise level. What unit is used to measure noise levels? How can an employee know if there is a problem with noise levels? Name an instrument to measure noise levels. Where else, other than at work, might you be exposed to high noise levels? (8 7) Page 9 of 10
12. Answer any two of the following (a), (b), (c) and (d). (a) (i) State Boyle s law. (9) (ii) Describe an experiment to show that pressure in a liquid increases with depth.(12) (iii) An air bubble rises from the bottom of a river. The volume of the air bubble is 20 mm 3 at the bottom of the river, where the pressure is 300 kpa. What is the volume of the air bubble near the surface of the water where the pressure is 100 kpa? (7) (b) (i) White light is made up of light of different colours. How would you show this? (9) (ii) Sunlight contains radiations that the human eye cannot see. Name two of these radiations. (6) (iii) Describe how to detect one of these radiations. (9) (iv) Give one use of this radiation. (4) (c) (i) Describe, with the aid of a diagram, an experiment to show that a force exists between electric charges. (12) (ii) What is meant by point discharge? (6) (iii) A lightning conductor is made from a thick copper strip. One end is pointed and the other end is put into the ground. Explain how a lightning conductor protects a building from being damaged by lightning. (10) (d) (i) What are x-rays? (6) (ii) The diagram shows an x-ray tube. Name the parts labelled A, B and C. (9) (iii) Explain what happens at A? (6) (iv) Give two uses of x-rays. High voltage (7) Low voltage A B C Page 10 of 10