if the magnification of an image formed by a lens is -1 if the distance of the image from the optical centre of the lens is 35 cm where is object place what is the nature and focal length of the lens if the object is displaced 20cm towards optical centre of the lens where would the image be formed what will be the its nature draw a diagram to justify your answer
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Mathmatical Statements Name: Class: Date: Time: 54 minutes Marks: 54 marks Comments: Page of 99
Scientists can use the visible light spectrum from distant stars to determine whether the stars are moving. The visible light spectrum from stars includes dark lines at specific wavelengths. (a) The diagram shows the visible light spectrum from the Sun and from four other stars, A, B, C and D. (i) Which star, A, B, C or D, is moving away from the Earth? () How does the speed of star B compare with the speed of star D? Tick ( ) one box. Tick ( ) The speed of star B is greater than the speed of star D. The speed of star B is less than the speed of star D. The speed of star B is the same as the speed of star D. () Page 2 of 99
(b) A radio wave is emitted by a star. The radio wave has a wavelength of 500 m and a frequency of 200 000 Hz. Calculate the speed of this radio wave. Choose the correct unit from the list below. m m / s m / s 2......... Speed =... unit... (3) (Total 5 marks) Page 3 of 99
2 The image below shows a solar thermal power station that has been built in a hot desert. The power station uses energy from the Sun to heat water to generate electricity. Energy from the Sun is reflected towards a solar receiver using many mirrors. Kim Steele/Photodisc/Thinkstock (a) (i) Which part of the electromagnetic spectrum provides most of the energy to heat the water in a solar thermal power station? () Describe how heated water is used to generate electricity by this solar thermal power station. The process is the same as in a fossil fuel power station. (3) Page 4 of 99
(b) A new type of solar power station, called a solar storage power station, is able to store energy from the Sun by heating molten chemical salts. The stored energy can be used to generate electricity at night. (i) It is important that the molten chemical salts have a high specific heat capacity. Suggest one reason why. () The solar storage power station can store a maximum of 2 200 000 kwh of energy. The solar storage power station can supply a town with a maximum electrical power of 40 000 kw. Calculate for how many hours the energy stored by the solar storage power station can supply the town with electrical power. Give your answer to 2 significant figures. Time =... hours (3) (iii) Table gives information about the place where the solar storage power station has been built. Season Mean number of daylight hours Table Mean power received from the Sun per square metre in kw Spring.5 0.90 Summer 3.5.0 Autumn 2.0 0.95 Winter 0.5 0.7 Page 5 of 99
The solar storage power station does not operate at the maximum possible electrical output every day of the year. Suggest why. (2) (c) Power stations do not work at maximum possible electrical output all the time.the capacity factor of a power station is calculated using the equation: Table 2 shows capacity factors for different types of power station. Table 2 Type of power station Renewable energy source Capacity factor Coal No 0.4 Natural gas No 0.48 Nuclear No 0.66 Solar thermal Yes 0.33 Tidal Yes 0.26 Wind turbine Yes 0.30 Page 6 of 99
(i) Compare the capacity factors of the renewable power stations with those of the non-renewable power stations in Table 2. Explain the reason for the difference between the capacity factors. (3) The capacity factor of a solar storage power station is higher than for all other renewable power stations. Suggest one reason why. () (Total 4 marks) Page 7 of 99
3 A can-chiller is used to make a can of drink colder. The image below shows a can-chiller. (a) The initial temperature of the liquid in the can was 25.0 C. The can-chiller decreased the temperature of the liquid to 20.0 C. The amount of energy transferred from the liquid was 6930 J. The mass of liquid in the can was 0.330 kg. Calculate the specific heat capacity of the liquid. Give the unit............. Specific heat capacity =... unit... (4) (b) Energy is transferred through the metal walls of the can of drink by conduction. Explain how......................... (4) Page 8 of 99
(c) The energy from the can of drink is transferred to the air around the can-chiller. A convection current is set up around the can-chiller. Explain how................... (3) (d) The can-chiller has metal cooling fins that are designed to transfer energy quickly to the surroundings. Give two features that would help the metal cooling fins to transfer energy quickly to the surroundings.... 2... (2) (Total 3 marks) Page 9 of 99