Magnetic Fields (OCR A Level Physics)

Exam Questions

10 mins5 questions
1
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1 mark

A student is doing an experiment on the magnetic force experienced by a current-carrying wire in a uniform magnetic field. The magnetic flux density B can be varied.

For a particular flux density, the current in the wire is 2.0 A. The length of the wire in the field is 0.12 m. The angle between the current and the magnetic field is 30°. The force experienced by the wire is 7.7 × 10−2 N.

The student calculates B and records the results in a table.

Which row shows the correct table heading for B and the correct value for B?

  Table heading for B Value for B
A B / T 0.37
B B / T 0.64
C B / Wb 0.37
D B / Wb 0.64

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    2
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    The diagram shows four magnetic compasses placed at the same distance from point X.

    q9-paper-2-june-2019-ocr-a-level-physics

    Which of the following is most likely to be at point X?

    • permanent magnet

    • current-carrying solenoid

    • current-carrying flat coil

    • straight current-carrying wire

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    3
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    A charged particle moves in a circular path of radius 1.2 cm in a uniform magnetic field.

    q10-paper-2-june-2018-ocr-a-level-physics

    The direction of the magnetic field is perpendicular to the plane of the paper.
    The particle has mass m, charge +Q and speed v.
    Another particle of mass 3m, charge +2Q and speed v moves in a circular path of radius R in the same magnetic field.

    What is the value of R?

    • 0.8 cm

    • 1.2 cm

    • 1.8 cm

    • 7.2 cm

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    4
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    The acceleration of a proton as it travels perpendicular to a magnetic field is 1.6 × 1014 m s-2. The flux density of the magnetic field is 0.37 T.

    What is the velocity of the proton?

    • 4.5 space cross times space 10 to the power of 6 m s-1

    • 3.0 space cross times space 10 to the power of 8 m s-1

    • 2.5 space cross times space 10 cubed m s-1

    • 1.7 space cross times space 10 to the power of 6 m s-1

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