D.4 Induction questions for IB Physics

68 questions on Induction, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.

  • IB Physics
  • Part of D Fields
  • HL only

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Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.

Question 1 · PHY-00910Paper 1A · 1 mark

A circular loop of wire of diameter 20 cm is held in a uniform magnetic field of strength 0.40 T. The plane of the loop makes an angle of 30° with the direction of the field. What is the magnetic flux through the loop?

  1. A

    6.3×10−3 Wb

  2. B

    1.1×10−2 Wb

  3. C

    1.3×10−2 Wb

  4. D

    2.5×10−2 Wb

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Question 2 · PHY-00006Paper 2 · 5 marks

A square coil of 200 turns and side 5.0 cm lies perpendicular to a uniform magnetic field. The field strength falls steadily from 0.40 T to zero in 0.25 s.

  1. (a)

    State Faraday’s law of electromagnetic induction.

    2 marks

  2. (b)

    Calculate the emf induced in the coil.

    3 marks

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Question 3 · PHY-00911Paper 1A · 1 mark

What is the weber, the unit of magnetic flux, expressed in SI base units?

  1. A

    kg s-2 A-1

  2. B

    kg m2 s-3 A-1

  3. C

    kg m2 s-2 A-1

  4. D

    kg m2 s-1 A-1

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Question 4 · PHY-00306Paper 2 · 7 marks

A small cylindrical magnet of mass 12 g is dropped from rest into the top of a long vertical copper tube. The magnet does not touch the walls of the tube. The magnet quickly reaches a constant speed of 0.25 m s−1 and falls through most of the tube at this speed.

  1. (a)

    Explain why the magnet reaches a constant speed.

    3 marks

  2. (b)

    Calculate the rate at which thermal energy is produced in the tube while the magnet falls at constant speed.

    2 marks

  3. (c)

    Outline how the direction of the induced currents is consistent with the principle of conservation of energy.

    2 marks

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Question 5 · PHY-00912Paper 1A · 1 mark

A flat search coil of 250 turns, each of area 2.0 cm2, is placed with its plane perpendicular to a magnetic field. The magnetic field strength increases uniformly from zero to 0.30 T in 15 ms. What is the magnitude of the emf induced in the coil?

  1. A

    1.0 mV

  2. B

    4.0 mV

  3. C

    1.0 V

  4. D

    100 V

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Question 6 · PHY-00326Paper 2 · 20 marks

A drop-tower ride at a theme park has a gondola of total mass 4200 kg, including the riders. The gondola is lifted at constant speed from the ground to the top of the tower, 100 m above the ground, in 50 s. It is then released from rest and falls freely for 62 m. In the next 28 m it passes through a braking section, where copper fins on the gondola pass between strong permanent magnets fixed to the tower. The gondola stops 10 m above the ground and is then lowered slowly to the ground.

A tall tower with a gondola at its top, 100 m above the ground. Labels show a free-fall section of 62 m, then a shaded braking section of 28 m with magnets on the tower, ending 10 m above the ground.

Air resistance and friction are negligible.

  1. (a)

    Calculate the useful power output of the motor that lifts the gondola.

    2 marks

  2. (b)

    The motor has an efficiency of 0.75 and is supplied from a 400 V supply. Calculate the current in the motor.

    2 marks

  3. (c)

    Show that the speed of the gondola as it enters the braking section is about 35 m s−1.

    2 marks

  4. (d)

    Explain how the magnets produce a braking force on the gondola.

    3 marks

  5. (e)

    Determine the average braking force on the gondola in the braking section.

    3 marks

  6. (f)

    Calculate the average deceleration of the gondola in the braking section, as a multiple of g.

    2 marks

  7. (g)

    Sketch a graph to show the variation with time of the speed of the gondola from its release until it stops. Numbers are not required on the axes.

    2 marks

  8. (h)

    The copper fins have a total mass of 180 kg. The specific heat capacity of copper is 385 J kg−1 K−1. Estimate the rise in temperature of the fins during one ride, assuming that all the energy removed in the braking section becomes internal energy of the fins.

    2 marks

  9. (i)

    Suggest why a mechanical brake is also needed to hold the gondola at rest at the end of the braking section.

    2 marks

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The notes on D.4 Induction

More questions in Fields

  1. D.1Gravitational fields
  2. D.2Electric and magnetic fields
  3. D.3Motion in electromagnetic fields
  4. D.4InductionThis page

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