Lesson 3.7.5.3

3.7.5.3 Magnetic flux and flux linkage Quiz: AQA Physics, Unit 7

20 questions

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Lesson 3.7.5.3, Magnetic flux and flux linkage: 20 multiple choice questions for the AQA Physics (7408), Unit 7: Fields and their consequences (A-level only), written with Revision Ninja.

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The 20 questions

  1. Magnetic flux through a flat area A in a uniform field B, with B normal to the area, is given by which expression?

    • BA
    • B + A
    • B^2 A
    • B/A
  2. Which unit is magnetic flux measured in?

    • tesla (T), equal to newton per ampere metre
    • henry (H), equal to volt second per ampere
    • farad (F), equal to coulomb per volt
    • weber (Wb), equal to tesla metre squared (T m^2)
  3. What is the flux linkage of a coil of N turns, each turn having flux Phi passing through it?

    • N^2 Phi
    • Phi/N
    • N Phi
    • N + Phi
  4. A coil of 200 turns has area 5.0 cm^2 in a field of 0.040 T normal to its plane. What is its flux linkage?

    • 2.0 x 10^-5 Wb
    • 4.0 x 10^-3 Wb
    • 1.0 x 10^-3 Wb
    • 4.0 x 10^-2 Wb
  5. A coil of 100 turns and area 0.010 m^2 is in a field of 0.20 T, with the coil normal at 60 degrees to the field. What is its flux linkage?

    • 0.10 Wb
    • 0.20 Wb
    • 0.0 Wb
    • 0.017 Wb
  6. A coil rotates until its plane is parallel to the field. What is its flux linkage at that position?

    • zero
    • NBA, the maximum value
    • NBA divided by two
    • 2NBA
  7. A coil of 50 turns and area 0.020 m^2 in a field of 0.30 T rotates from normal alignment to a position with its plane parallel to the field. What is the change in flux linkage?

    • 0.15 Wb
    • 0.30 Wb
    • 0.60 Wb
    • 0.0 Wb
  8. A graph of flux linkage against the angle between a coil's normal and the field is what shape?

    • a constant line at NBA for all angles
    • a cosine curve, with its maximum when the coil normal is parallel to the field
    • a sine curve, with its maximum when the coil plane is parallel to the field
    • a straight line falling to zero at 90 degrees
  9. Magnetic flux density is the flux per unit area measured in which orientation?

    • at 45 degrees to the surface
    • parallel to the length of the conductor
    • parallel to the velocity of the charge
    • normal to the field direction
  10. A flat loop of area 0.10 m^2 is normal to a uniform field of 0.50 T. What is the flux through it?

    • 0.0050 Wb
    • 5.0 Wb
    • 0.20 Wb
    • 0.050 Wb
  11. A 500-turn coil of area 0.0020 m^2 lies in a field of 0.080 T with its normal along the field. What is the maximum flux linkage?

    • 0.080 Wb
    • 0.80 Wb
    • 0.16 Wb
    • 0.00080 Wb
  12. Two identical coils of areas and field orientation the same have 100 and 200 turns. What is the ratio of their flux linkages?

    • 2:1
    • 1:1
    • 1:4
    • 1:2
  13. A coil of area 0.040 m^2 is in a field of 0.20 T. The normal to the coil is 30 degrees from the field. What is the flux through the coil?

    • 3.5 x 10^-3 Wb
    • 8.0 x 10^-3 Wb
    • 6.9 x 10^-3 Wb
    • 4.0 x 10^-3 Wb
  14. Why is flux linkage defined as N Phi rather than Phi alone?

    • Each turn links the whole flux, so the contributions add up over the N turns
    • Only the outermost turn links the flux, so N acts as a correction factor
    • Each turn sits in a different field, so the flux must be multiplied by N
    • Flux linkage is a separate quantity that measures the density of the field
  15. A coil of 300 turns and area 6.0 cm^2 lies normal to a field of 0.25 T. What is its flux linkage?

    • 0.045 Wb
    • 0.18 Wb
    • 0.45 Wb
    • 0.0045 Wb
  16. A coil's flux linkage is measured for the same flux through each turn. What happens to flux linkage when the number of turns is doubled?

    • It quadruples
    • It is unchanged
    • It doubles
    • It halves
  17. In Required Practical 11, a search coil is turned about an axis in the field. What does the change of flux linkage with angle show?

    • The coil's orientation to the field changes the flux linkage as NBA cos(theta)
    • The field strength varies with time as the coil turns
    • The coil's resistance changes as it rotates in the field
    • The coil's mass changes the flux through it
  18. A coil of 2 turns, each of area 0.010 m^2, lies in a field of 0.40 T with its normal at 60 degrees to the field. What is its flux linkage?

    • 1.6 x 10^-2 Wb
    • 4.0 x 10^-3 Wb
    • 2.0 x 10^-3 Wb
    • 8.0 x 10^-3 Wb
  19. The flux through a 10-turn loop changes from 0.12 Wb to 0.02 Wb. What is the change in flux linkage?

    • -1.0 Wb
    • +1.0 Wb
    • -0.10 Wb
    • -0.010 Wb
  20. A coil has flux linkage 0.30 Wb with its normal along the field. What is the flux linkage when its normal is at 60 degrees to the field?

    • 0.52 Wb
    • 0.30 Wb
    • 0.15 Wb
    • 0.26 Wb

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