5054_s19_qp_22
A paper of Physics, 5054
Questions:
11
Year:
2019
Paper:
2
Variant:
2

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is a diagram of a soldering iron. Solder is a mixture of metals used to make a permanent contact between electrical wires. heating element metal tip The heating element raises the temperature of the metal tip. When solder is placed against the tip, the solder melts over the wires to be joined. When the solder cools, it solidifies and the permanent connection is made. The working temperature of the metal tip is 380 °C. The boxes in show two materials and some different melting points. melting point 1000 °C solder metal of the metal tip 380 °C 200 °C 20 °C 0 °C material On , draw a line from the metal of the metal tip and a line from the solder to a suitable melting point for each. The heating element is rated at 24 V, 3.3 A. The heating element is switched on. The temperature of the metal tip rises from 20 °C to 320 °C in the first 10 s. Calculate the electrical energy supplied to the heating element in the first 10 s. energy = The metal tip is made of copper and has a mass of 2.3 g. The specific heat capacity of copper is 0.39 J / (g °C). Calculate the thermal energy gained by the metal tip in the first 10 s. thermal energy = Describe, in terms of free electrons, the process by which heat transfers through the metal tip. Heat is lost from the metal tip by convection in the air. Explain how convection occurs in the air. The temperature of the metal tip is measured with a thermocouple. In the space below, draw a labelled diagram of a thermocouple. Mark with a letter H the part of the thermocouple that is placed on the metal tip. State two reasons why a thermocouple thermometer is suitable for measuring how the temperature of the metal tip varies during the first 10 s. 1. 2.
11
Stars are formed inside a cloud of gas and dust in space. When a star forms, the cloud first becomes smaller as it collapses. State what causes the gas cloud to collapse. Eventually nuclear fusion occurs in the star. State two conditions required for nuclear fusion to occur in the star. 1. 2. When a large star explodes, nuclei of heavy elements are formed. One such nucleus is uranium-235 (23 2U). State the name and the number of each type of particle found in one nucleus of 23 2U. name of particle number found in nucleus name of particle number found in nucleus State one feature that is the same for the nuclei of all isotopes of uranium. A nucleus of 23 2U in a nuclear reactor can undergo nuclear fission. Describe the process of nuclear fission in a nuclear reactor. State one difference between nuclear fusion and nuclear fission. The nucleus of 23 2U is not stable. It decays by the emission of an alpha-particle (α) into a nucleus of thorium (Th). Complete the nuclear equation that represents this decay. 2U Th + 2 α Geiger and Marsden carried out an experiment to investigate the scattering of alpha-particles. shows a diagram of the apparatus that they used. vacuum thin gold foil fluorescent screen radioactive source beam of alpha-particles When an alpha-particle strikes the fluorescent screen a flash of light is emitted. On , mark with a letter P where most flashes occur on the screen. Describe what is seen on the other parts of the screen. State two conclusions about atoms of gold that resulted from this experiment.