OCR A Level Physics

Topic Questions

A LevelPhysicsOCRTopic Questions4. Electrons, Waves & Photons4.1 Charge & Current

4.1 Charge & Current

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11 mark

Which sequence shows the materials arranged in the order of increasing number density of charge carriers?

increasing number density rightwards arrow from blank to blank of

  • conductor, insulator, semiconductor

  • conductor, semiconductor, insulator

  • insulator, semiconductor, conductor

  • semiconductor, insulator, conductor

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21 mark

Which law indicates that charge is conserved?

  • Lenz’s law

  • Coulomb’s law

  • Kirchhoff’s first law

  • Faraday’s law of electromagnetic induction

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31 mark

The diagram below shows the motion of positive and negative particles in a conducting solution.

q1-paper-2-june-2017-ocr-a-level-physics

Which statement is correct?

  • The current in the solution is zero.

  • The conventional current is to the left.

  • The positive particles are always protons.

  • The negative particles are always electrons.

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1
Sme Calculator1 mark

Wires P and Q, made from the same metal, are connected in parallel across a cell of negligible internal resistance.

The table shows some data.

Wire Length of wire Diameter of wire Mean drift velocity of electrons in the wire/mms–1
P L d 0.60
Q 3L 2d v

What is the mean drift velocity v of the electrons in wire Q?

  • 0.15 mm s–1

  • 0.20 mm s–1

  • 0.30 mm s–1

  • 0.60 mm s–1

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2
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An aluminium wire of length 1.0 m and uniform cross-section is connected to a power source with an e.m.f of 5.0 V and negligible internal resistance.

The electron number density of aluminium is 1.81 × 1029 m-3

The resistivity of aluminium is 2.63 × 10-8 Ω m

What is the mean drift velocity of electrons through the resistor?

  • 6.6 × 10-3 mm s-1

  • 0.6 mm s-1

  • 3.3 mm s-1

  • 6.6 mm s-1

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3
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The graph below shows the variation of current I against time t for a circuit constructed from a variable voltage source in series with a resistor of fixed resistance.

4-1-mcq-h-q2-ocr-al-physics

Which of the following graphs represents the variation of charge against time for the circuit?

  • 4-1-mcq-h-q2a-ocr-al-physics

  • 4-1-mcq-h-q2b-ocr-al-physics

  • 4-1-mcq-h-q2c-ocr-al-physics

  • 4-1-mcq-h-q2d-ocr-al-physics

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4
Sme Calculator1 mark

An negatively charged particle is emitted initially at rest from a negatively charged plate towards a positively charged plate separated by a distance d. The voltage across the plates is equal to V. 

Which of the following statements about the electron are correct?

  1. The time it takes for the electron to travel from the anode to the cathode depends on the square root of the particles mass to charge ratio 

  2. Doubling the voltage results in the time it takes for the electron to reach the cathode to increase by a factor of square root of 2

  3. Reducing the charge of the particle travelling between the electrons by a factor of 4 reduces the average current between the plates over the time it takes for the electron to pass between the electrodes by a factor of 8

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1 and 3

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1
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Part of an electric circuit is shown below.

q3-paper-2-june-2019-ocr-a-level-physics

The direction of all the currents and the magnitude of two currents are shown.

How many electrons pass through the point Y in 10 s?

  • 1.25 × 1018

  • 2.50 × 1018

  • 3.75 × 1018

  • 5.00 × 1018

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2
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A battery delivers 1200 C of electric charge to a circuit in 5 minutes. Calculate the average current in the circuit over those 5 minutes.

  • 20 A

  • 240 A

  • 4 A

  • 6000 A

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3
Sme Calculator1 mark

A constant 5 A current source fully charges a metal plate by supplying it with 6.25 × 1020 electrons.

Calculate the time it takes the current source to fully charge the metal plate.

  • 500 s

  • 20 s

  • 150 s

  • 5 s

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4
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A circuit consists of a battery attached to a wire with circular cross-section of unknown material placed in series with an ammeter. The results of a previous experiment using the same experimental apparatus indicate that the mean drift velocity of electrons through the wire is 1.04  10-4 m s-1. The ammeter measures a reading of 10.0 A and the diameter of the wire is measured to be 3.00 mm.

Which of the materials listed in the table below is the wire likely to be made of?

Material

Electron number density, n / m-3

Gold

5.90 × 1028

Copper

8.51 × 1028

Iron

1.70 × 1029

Aluminium

1.81 × 1029

  • Gold

  • Copper

  • Iron

  • Aluminium

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5
Sme Calculator1 mark

Which of the following statements is/are correct?

  1. Conductors have higher electron number densities than semiconductors.
  2. Insulators have higher electron number densities than semiconductors.
  3. Semiconductors have electron number densities between insulators and conductors.

  • Only 1

  • 1 and 2

  • 1 and 3

  • 1, 2 and 3

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