OCR A Level Physics

Topic Questions

A LevelPhysicsOCRTopic Questions4. Electrons, Waves & Photons4.5 Potential Dividers

4.5 Potential Dividers

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1
Sme Calculator1 mark

In a potential divider circuit, two resistors in series connect to a voltage source Vin. The ratio of the output voltage to the input voltage across the second resistor to the first resistor is  1 fifth. 

The first resistor is replaced with one which has twice the resistance, the second resistor is replaced with one which has triple the resistance, and the input voltage source is doubled.

What is the new value of the ratio of output voltage to input voltage for the second resistor?

  • 1 over 11

  • 3 over 11

  • 3 over 8

  • 3 over 5

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2
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The potential divider circuit below consists of a resistor of resistance R in series with a pair of resistors with resistances R and r in parallel with each other. The cell can be assumed to have negligible internal resistance.

4-5-mcq-h-q2-ocr-al-physics

What is the ratio of the voltage across the voltmeter to the voltage across the cell?

  • fraction numerator 2 r over denominator R space plus space r end fraction

  • fraction numerator r over denominator 2 R space end fraction

  • fraction numerator r over denominator R space plus space 2 r end fraction

  • fraction numerator 2 r over denominator 2 R space plus space r end fraction

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3
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A potential divider circuit powered by a cell of e.m.f Ɛ and negligible internal resistance is built in which the output of the divider acts as the input voltage to a second potential divider as shown in the diagram.

4-5-mcq-h-q3-ocr-al-physics

The formula for the resistance of each of the resistors in the circuit is given by the formula: Rn = nR

Which expression is correct for the current passing through the resistor labelled R4?

  • fraction numerator 2 straight Ɛ over denominator 23 R end fraction

  • fraction numerator 6 straight Ɛ over denominator 23 R end fraction

  • fraction numerator 8 straight Ɛ over denominator 23 R end fraction

  • fraction numerator 14 straight Ɛ over denominator 23 R end fraction

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4
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A student constructs a potential divider circuit powered by a cell of e.m.f Ɛ consisting of an LDR resistor of resistance RLDR in series with a parallel combination of another identical LDR and a fixed resistor of resistance R as shown in the diagram below.

A student has a variable light-source that illuminates the two LDRs equally. The student knows that RLDR is inversely proportional to the light intensity L incident on the LDRs.

4-5-mcq-h-q4-ocr-al-physics

Which of the following graphs represents the data for Vout as a function of L?

4-5-mcq-h-ma4-ocr-al-physics

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1
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A potential divider circuit is shown below.

q5-paper-2-june-2019-ocr-a-level-physics

The resistance of the variable resistor is R. The potential difference across the variable resistor is V.

Which graph shows the correct variation with R of V ?

q5-2-paper-2-june-2019-ocr-a-level-physics

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2
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A student is investigating a potential divider circuit.

He connects a battery with a thermistor and resistor as shown in Figure 1 below.

Figure 14-5-mcq-m-q1-ocr-al-physics

The resistance of the resistor is 10Ω and the resistance of the thermistor is 15Ω. The potential difference (p.d.) across the thermistor is 6.0 V. What is the electromotive force(e.m.f) of the battery?

  • 4 V

  • 9 V

  • 10 V

  • 15 V

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3
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A circuit is made to investigate the range of a variable resistor in Figure 2.

The student makes a circuit where a variable resistor and fixed resistor are connected to a 9.0 V supply of negligible internal resistance.

Figure 2

4-5-mcq-m-q2-ocr-al-physics

What range of voltages can be obtained between X and Y?

  • Zero to 1.5 V

  • Zero to 7.5 V

  • 1.5 V to 7.5 V

  • 1.5 V to 9.5 V

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4
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A researcher designs an experimental circuit (Figure 3) to explore the correlation between voltage and variations in temperature and light intensity. The voltage across the thermistor and light-dependent resistor (LDR) is expected to fluctuate in response to changes in temperature and light conditions.

Figure 3

4-5-mcq-m-q3-ocr-al-physics

What conditions do the student need to create to ensure the reading on V1 and V2 are both low?

  Temperature Light level
A low low
B low high
C high low
D high high

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5
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An individual is conducting an examination of a potential divider circuit, comprising a light-dependent resistor (LDR) and a fixed resistor, illustrated in Figure 4.

Figure 4

4-5-mcq-m-q4-ocr-al-physics

The voltmeter reading has increased. What has happened to the light intensity and resistance of the LDR to cause this?

  • The light intensity decreases and the LDR resistance decreases.

  • The light intensity decreases and the LDR resistance increases.

  • The light intensity increases and the LDR resistance decreases.

  • The light intensity increases and the LDR resistance increases.

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