A resistor is described as being ‘ohmic’. Which of the following statements does NOT apply to it?When the potential difference across the resistor doubles, the current through it will double too (so long as the temperature and other physical conditions do not change)The current through the resistor is inversely proportional to the potential difference across itA graph of I against V for the component will be a straight line through the originWhen the p.d. across the component is increased from 2 to 4 V, the current through it will increase from 1.2 to 2.4 A2A variable resistor is set to a value of 5 ohms, and a current-voltage (I-V) graph (with I on the y-axis and V on the x-axis) is plotted for it. Its resistance is then doubled to 10 ohms. What effect will this have on its I-V graph?It will have no effect on its I-V graphThe slope (gradient) of the graph will increaseThe entire graph will move upwardsThe slope (gradient) of the graph will decrease3If a current of 4 A flows through a motor when a potential difference of 12 V is applied across it, calculate its resistance.0.33 Ω3 Ω48 Ω6 Ω4A student wishes to measure the resistance of a filament bulb. Which of the following should they do?Connect an ammeter and a voltmeter, both in seriesConnect a voltmeter in parallel and an ammeter in seriesConnect a voltmeter in series and an ammeter in parallelConnect an ammeter and a voltmeter, both in parallel5Which of the following does NOT require the use of an LDR?A smartphone screen with an automatic brightness settingA thermostatThe automatic headlights on a carThe shutter of a digital camera6A student connects a cell, a filament bulb and a diode in series to one another. The diode is forward-biased. What will happen to the bulb when the leads attached to the diode are swapped around?It will flash on and offIt will get brighterNothing (its brightness will not change)It will turn off
Question
A resistor is described as being ‘ohmic’. Which of the following statements does NOT apply to it?When the potential difference across the resistor doubles, the current through it will double too (so long as the temperature and other physical conditions do not change)The current through the resistor is inversely proportional to the potential difference across itA graph of I against V for the component will be a straight line through the originWhen the p.d. across the component is increased from 2 to 4 V, the current through it will increase from 1.2 to 2.4 A2A variable resistor is set to a value of 5 ohms, and a current-voltage (I-V) graph (with I on the y-axis and V on the x-axis) is plotted for it. Its resistance is then doubled to 10 ohms. What effect will this have on its I-V graph?It will have no effect on its I-V graphThe slope (gradient) of the graph will increaseThe entire graph will move upwardsThe slope (gradient) of the graph will decrease3If a current of 4 A flows through a motor when a potential difference of 12 V is applied across it, calculate its resistance.0.33 Ω3 Ω48 Ω6 Ω4A student wishes to measure the resistance of a filament bulb. Which of the following should they do?Connect an ammeter and a voltmeter, both in seriesConnect a voltmeter in parallel and an ammeter in seriesConnect a voltmeter in series and an ammeter in parallelConnect an ammeter and a voltmeter, both in parallel5Which of the following does NOT require the use of an LDR?A smartphone screen with an automatic brightness settingA thermostatThe automatic headlights on a carThe shutter of a digital camera6A student connects a cell, a filament bulb and a diode in series to one another. The diode is forward-biased. What will happen to the bulb when the leads attached to the diode are swapped around?It will flash on and offIt will get brighterNothing (its brightness will not change)It will turn off
Solution
The text you provided is a series of multiple-choice questions related to electrical circuits and components. Here are the answers:
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The statement that does NOT apply to an ohmic resistor is "The current through the resistor is inversely proportional to the potential difference across it". In an ohmic resistor, the current is directly proportional to the potential difference, not inversely.
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If the resistance of a variable resistor is doubled from 5 ohms to 10 ohms, the slope (gradient) of the I-V graph will decrease. This is because the slope of the I-V graph represents the resistance, so if the resistance increases, the slope decreases.
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If a current of 4 A flows through a motor when a potential difference of 12 V is applied across it, its resistance can be calculated using Ohm's law (V = IR). So, R = V/I = 12V/4A = 3 Ω.
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To measure the resistance of a filament bulb, a student should connect a voltmeter in parallel and an ammeter in series. This allows the student to measure the potential difference across the bulb and the current through it, which can be used to calculate resistance.
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The use of an LDR (Light Dependent Resistor) is not required in a thermostat. LDRs are used in devices that need to respond to changes in light levels.
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If a student connects a cell, a filament bulb, and a diode in series and the diode is forward-biased, swapping the leads attached to the diode will turn off the bulb. This is because the diode will be reverse-biased and will not allow current to flow through the circuit.
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