UNIQUE SCIENCE ACADEMY

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1 1 (a) UNIQUE SIENE EMY Test (Unit 12) Name :... Paper: Physics ate :... lass: 1 Time llowed: 35Minutes Maximum Marks: 25 Theory Section: [Total 16 Marks] Fig. 1.1 shows a beaker in which coffee is served at an airport kiosk. 1 section through beaker layer of corrugated cardboard stuck to a layer of smooth cardboard, with air trapped between them Fig. 1.1 Fig. 1.2 The beaker itself is made of two layers of cardboard, as shown in section in Fig It has a thin plastic lid. (i) State two sources of loss that are reduced by the lid [2] (b) (i) State two reasons why the layer of corrugated cardboard stops the fingers of the person holding the beaker from becoming uncomfortably [2] State the meaning of the term thermal capacity [2] nother airport kiosk serves coffee in pottery mugs. The mugs all have the same internal dimensions but some have a high thermal capacity and some have a low thermal capacity. When drinks are poured into the mugs, the temperature of the drink always drops because of the thermal energy absorbed by the mug. State which mug, high thermal capacity or low thermal capacity, causes the least fall in temperature of the drink, and explain why. mug... explanation... [2] [Total: 8]

2 2 2 n electric soldering iron is used to melt solder, for joining wires in an electric circuit. soldering iron is shown in Fig copper tip metal cylinder with er coil inside plastic handle lead to Fig. 2.1 electricity supply Solder is a metal which melts easily. The er coil inside the metal cylinder s the copper tip. (a) (i) Suggest why the tip is made of copper.... [1] Suggest why the handle is made of plastic.... [1] (b) The er coil is switched on. When the tip is put in contact with the solder, some of the is used to melt the solder. (i) State the process by which the is transferred from the copper tip to the solder.... [1] y which process or processes is the rest of the transferred to the surroundings? Tick the boxes alongside any of the following (you may tick as many as you think are correct). conduction convection evaporation radiation [2]

3 3 (c) short time after switching on the soldering iron, it reaches a steady temperature, even though the er coil is constantly generating. The soldering iron is rated at 40 W. What is the rate at which is being lost from the soldering iron? Tick one box. greater than 40 W equal to 40 W less than 40 W [1] (d) Explain briefly the term radiation [2] [Total: 8] MQ SETION: [Total 9 Marks] bar made of half wood and half copper has a piece of paper wrapped tightly round it. The bar is ed strongly at the centre for a short time, and the paper goes brown on one side only. wood paper copper Which side goes brown, and what does this show about wood and copper? brown side wood copper copper conductor insulator copper insulator conductor wood conductor insulator wood insulator conductor

4 2 The diagrams show part of a -ing system which is working by convection. Which diagram shows the most likely flow of in the system? 4 3 The diagram shows a block of ice placed in a warm room. t which point is the temperature the lowest? clamp ice table 4 read can be cooked by placing it below, but not touching, a ing element. ing element bread Which process transfers thermal energy from the ing element to the bread? conduction insulation convection radiation

5 5 5 The diagram shows a refrigerator. The cooling unit is placed at the top. The cooling unit cools the air near it. cooling unit What happens to the density of this air as it cools and how does it move? density of the air movement of the air decreases moves down decreases stays where it is increases moves down increases stays where it is 6 teacher demonstrates convection currents using a box with two chimneys and a lighted candle. She holds a smoking taper at point P. In which direction does the convection current cause the smoke to move? P chimney chimney

6 6 7 Hot liquid in a vacuum flask cools extremely slowly. This is because some methods of transfer cannot take place in a vacuum. Which methods cannot take place in a vacuum? conduction and convection only conduction and radiation only convection and radiation only 8 conduction, convection and radiation beaker of is ed at its base. Why does the at the base rise? It contracts and becomes less dense. It contracts and becomes more dense. It expands and becomes less dense. 9 It expands and becomes more dense. ing element is positioned in a narrow sealed tube of liquid. What would be the best place to position the ing element in order to obtain the best circulation of the liquid through the tube? liquid MQ nswer Sheet