basicassasin
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I've done the exam but don't have the answer to check if its right? pretty sure im wrong
Question 22 (3 marks) In Australia, free to air television has recently had many more channels become available. Also, over the past decade, millions more people are using mobile phones. Discuss problems presented by the limited range of frequencies in the electromagnetic spectrum available for such purposes, and explain how such problems have been overcome. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... Question 23 (2 marks) In the space below, use a diagram to show how the ionosphere can be used to increase the range of communication using certain waves. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... | Marks 3 2 |
Question 24 (4 marks) Encoding methods are used in many modern communication technologies. Identify one such technology that has been studied and describe the underlying physical principles used in its application. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... Question 25 (4 marks) Describe two ways in which electricity can be generated for isolated communities that do not have access to the power grid, and identify some advantages and disadvantages of both. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... | Marks 4 4 |
Question 26 (3 marks) Two charges, M and N, are arranged as shown.
(a) On the diagram, place a “X” where the direction of the electric field would be pointing directly to the north. (b) When an electron is placed at the point Y, it experiences a force of 4.8 x 10-23 N. Calculate the magnitude and direction of the electric field at Y. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... Question 27 (2 marks) Describe the function of an iron core in the operation of a simple electromagnet. Diagrams should be used to illustrate your answer. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... | Marks 1 2 2 |
Question 28 (3 marks) A model heating coil was immersed in an insulated beaker with 200 mL of water. The time it took to heat the water from 20.0 oC to 25.0 oC was recorded for different voltage settings on the power pack supplying the heating coil. The results are shown in the table.
(a) Identify the quantity that must also be measured so that the power of the heating coil can be calculated. ....................................................................................................................................... (b) Assuming that the resistance of the heating coil remains constant throughout the investigation, describe the relationship between the voltage applied to the heating coil and its power. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... | Marks 1 2 |
Question 29 (5 marks) A velocity versus time graph for a car moving along a straight road is shown.
v (m s-1)
6 9 12 15 18 21
(a) Find the car’s displacement at t = 9.0 seconds. Show your working and explain how you used the graph to calculate your answer. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (b) At time = 0, the car’s displacement = 0. On the axes below, sketch a graph of the car’s displacement (x) versus time.
x (m) 6 9 12 15 18 21 | Marks 2 3 |
Question 30 (5 marks) Many people die every year on Australian roads when their vehicles fail to negotiate a curve in the road. Authorities often state that speed was a factor in the crash. (a) A particular curve in a road has a radius of 100 m. It is signposted as being safe at 60 km h-1 . What would the radius of curvature for this curve need to be changed to so that it could be safely negotiated at 90 km h-1 ? ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (b) Explain why vehicles with a larger mass need to adhere more closely to the advised speed. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... Question 31 (4 marks) The law of conservation of energy applies to the motion of vehicles. (a) Find the work done on a 1200 kg vehicle when it slows from 90 km h-1 to 50 km h-1 in 8.0 seconds. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... Question 31 continues on page 19. Question 31 (continued) (b) Explain why the brakes of a car in stop-start city traffic get very hot. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... Question 32 (6 marks) (a) “Astronomers realised long ago that the distance to stars visible to the naked eye is huge and varies enormously.” Justify this statement with reference to the two factors which determine the brightness of stars. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (b) Explain why astronomers believe that red giant stars are nearing the end of their lives as true stars. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... | Marks 3 2 2 Marks 2 3 3 |
Question 33 ( 5 marks) Following the devastating earthquake and tsunami which damaged a nuclear power plant in Japan, only protected workers were allowed to approach closer than 30km. (a) Explain which type of radiation authorities would be most concerned about to make them enforce a 30 km exclusion zone around the nuclear power plant. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (b) Outline a first-hand investigation in which one identified property of different types of nuclear radiation could be compared. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... Question 34 (3 marks) With reference to the Scientific Method, explain what features of an investigation must be ensured so that the results of the investigation are valid. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... | Marks 2 3 3
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