4.3.3. Action and use of circuit components
A subsection of Physics, 5054, through 4. Electricity and magnetism
Listing 10 of 34 questions
shows a 9.0 V battery connected in series with a 16.0 Ω resistor and a small metal conductor X at room temperature. V 16.0 Ω X 9.0 V A voltmeter measures the potential difference (p.d.) across the 16.0 Ω resistor. At room temperature the resistance of X is 4.0 Ω. Calculate the current supplied by the battery. Calculate the p.d. across the 16.0 Ω resistor. X is heated slowly to a very high temperature. Sketch a graph to show how the resistance of a metal conductor depends on its temperature. State and explain how the voltmeter reading changes as the temperature of X rises. Suggest a suitable range for the voltmeter. There is a choice of part on the following page. EITHER Describe in outline how the circuit in can be used as a thermometer. State two advantages of a thermometer such as this over a liquid-in-glass thermometer. The change in voltmeter reading with temperature is non-linear. Explain what is meant by non-linear. OR The voltmeter is removed from the circuit in and the negative terminal of the battery is earthed. A connection is made from the circuit to the inputs A and B of a NAND gate. The output of the NAND gate is connected to an LED (light-emitting diode) and a resistor. This is shown in . 16.0 Ω X 9.0 V LED A B Draw the truth table for a NAND gate. The LED is lit. State the inputs at A and B and explain why these inputs cause the LED to light. X is slowly heated to a very high temperature. At a certain temperature, the LED switches off. Explain why this happens.
5054_w09_qp_2
THEORY
2009
Paper 2, Variant 0
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A thermocouple thermometer is made from two different metals and a voltmeter. One junction of the thermocouple thermometer is placed in a beaker containing a mixture of water and ice. The other junction is placed inside a high-temperature furnace, as shown in . metal 1 metal 2 water and ice high- temperature furnace V The thermocouple thermometer has a linear output over the operating temperature range of the furnace. State what, for a thermocouple thermometer, is meant by a linear output. The junction inside the furnace is at temperature T. shows the reading V of the voltmeter at two values of T that are within the operating temperature range of the furnace. T / °C V / mV 6.20 7.70 When the furnace is operating at a high temperature, the furnace door is opened and the reading of the voltmeter falls to 6.80 mV. Calculate the temperature of the junction inside the furnace. temperature = State why a liquid-in-glass thermometer is not used to measure the temperature inside the furnace.
5054_w12_qp_21
THEORY
2012
Paper 2, Variant 1
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11 An ammeter, a variable resistor and a 4.0 Ω resistor are connected in series with a 6.0 V battery. A cathode-ray oscilloscope (c.r.o.) is connected in parallel with the 4.0 Ω resistor through a switch. is the circuit diagram. A 6.0 V switch c.r.o. 4.0 Ÿ The switch is open. The variable resistor is adjusted so that it has a resistance of 8.0 Ω. Calculate the current measured by the ammeter, current = the potential difference (p.d.) across the 4.0 Ω resistor. p.d. = The resistance of the variable resistor is adjusted until the p.d. across the 4.0 Ω resistor is 5.0 V. State the effect that this adjustment has on the current measured by the ammeter, the resistance of the variable resistor. The trace on the c.r.o. is a horizontal line across the middle of the screen and the p.d. across the 4.0 Ω resistor is still 5.0 V. The Y-gain control is set at 2.0 V / cm and the switch is closed. State the effect on the trace of closing the switch. shows, in outline, the basic structure of a c.r.o. viewed from the side. ILODPHQW HOHFWURQEHDP On write, in the five empty boxes, the names of the parts of the c.r.o. indicated. Explain how the electron beam is produced. Explain why the tube of the c.r.o. must be evacuated. Question 11 continues on page 16. In the c.r.o. shown in , the electrons travel from left to right. 1. Explain why the flow of electrons is an electric current. 2. State the direction of the conventional current due to the electrons.
5054_w13_qp_21
THEORY
2013
Paper 2, Variant 1
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Questions Discovered
34