4.3. Electric circuits
A subsection of Physics, 5054, through 4. Electricity and magnetism
Listing 10 of 85 questions
shows two circuit components. LDR thermistor For each of these components state what causes an increase in its resistance. thermistor LDR shows a battery connected to a diode, an ammeter and a resistor. shows the current – voltage graph for the diode. A current voltage / V 0.6 The current in the resistor is 2.0 A and the potential difference across the resistor is 5.4 V. State what is meant by the electromotive force (e.m.f.) of the battery. Explain why the e.m.f. of the battery must be greater than 5.4 V. Calculate the electrical energy input to the resistor in 5.0 minutes. energy input = The circuit is reconnected with the diode in the opposite direction, as shown in . A Explain what is observed.
5054_s21_qp_21
THEORY
2021
Paper 2, Variant 1
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shows a potential divider circuit containing two resistors R1 and R2. input voltage 6.0 V output voltage R1 R2 There is an input voltage of 6.0 V. Complete Table 8.1 to show the output voltage for different values of the resistances of the two resistors. Table 8.1 resistance of R1 / Ω resistance of R2 / Ω output voltage / V 8.0 8.0 EITHER In the circuit shown in , resistor R1 is replaced by a light dependent resistor (LDR). In the space below, draw the circuit symbol for an LDR. The LDR is moved from darkness into daylight. State what happens to the resistance of the LDR and the output voltage. resistance output voltage A potential divider circuit can also be used to produce an output voltage that changes with temperature. State the name of the component that is used instead of the LDR. OR A simple bistable circuit contains NOR gates. In the space below, draw the circuit symbol of a NOR gate. Describe what is meant by a bistable circuit.
5054_s21_qp_22
THEORY
2021
Paper 2, Variant 2
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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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Questions Discovered
85