Gobezoch › Textbooks › Physics Grade 12

Physics Grade 12 Unit 4: Electromagnetism

national exam questions have come from this unit. It runs 25 pages; one careful study pass takes about 3.0 hours, and its difficulty is easier among Physics units. Each section below lists the questions set from it, with the year, and opens the page that teaches it.

Read this unit
4.1 Magnets and Magnetic field · read p. 118
Not asked in a national paper yet.
4.2 Magnetic field lines · read p. 120
Not asked in a national paper yet.
4.3 Current and Magnetism · read p. 122
  • 2018 E.C., Q9 – If the magnitude of magnetic field produced at a distance of 2 cm from a long straight current carrying wire is 1.2 T, then what is the magnitude of magnetic field at a distance of 3 cm from the wire?
  • 2017 E.C., Q40 – A long straight wire carries a current of 5.0 A. What is the magnetic field strength produced by the current at a μ = 0 4π × 10 T\cdotpm/A −7 distance of 2.0 cm from the wire? (Magnetic permeability free space ) 5π × 10
  • 2014 E.C., Q13 – Consider a long and tightly wound solen ind length L and N turghtly wound solenoid carrying current I, having length, which of the following describes the magnetic field produced by the solenoid?
  • 2005 E.C., Q25 – The loop carries a current labelled i, drawn clockwise: an arrowhead on the top side points to the right, an arrowhead on the right side points down, an arrowhead on the bottom side points to the left, and an arrowhead o
4.4 Electromagnetic Induction · read p. 126
Not asked in a national paper yet.
4.5 Faraday’s Law of electromagnetic Induction · read p. 129
  • 2013 E.C., Q8 – A coil and a permanent magnet are set in relative motion. Which one of the following statement is NOT correct about induced electromotive force?
  • 2008 E.C., Q35 – The torque experienced by a current carrying loop, in an external, magnetic field is:
4.6 Transformers · read p. 131
  • 2018 E.C., Q10 – Suppose a 50 Hz outlet voltage of 10,000 V needs to be reduced to 220 V using a stepdown transformer. How many turns does the primary coil on the transformer have if the secondary coil has 110 turns?
  • 2016 E.C., Q4 – Which one of the following statements is correct about actions of A.C. and D.C. generators?
  • 2014 E.C., Q23 – The primary coil of a transformer has 250 turns and its secondary coil consists of 1500 turns. If 220 V is applied to its primary coil, the voltage induced in the secondary coil, respectively, are
  • 2013 E.C., Q9 – What is the advantage of using alternating current in transmission of electric energy?
  • 2006 E.C., Q30 – A 6V battery is connected across the primary coil of a transformer having 50 turns. If the secondary coil of the transformer has 100 turns, what voltage appears across the secondary?
  • 2005 E.C., Q13 – A step-up transformer is used to
4.7 Application and safety · read p. 134
  • 2018 E.C., Q6 – For a coil placed in a variable magnetic field, Lenz's law states that the direction of the induced current in the coil is in such a way as to:
  • 2017 E.C., Q12 – A circular coil is located in a uniform magnetic field of magnitude $0.50\,\text{T}$ directed perpendicular to the plane of the coil. If the area of the coil changes with uniform rate, in such a way that it increases by
  • 2015 E.C., Q38 – A magnetic field intensity of 4x10⁻⁴ T crosses a coil having face area 100 cm² and 5x10⁴ turns perpendicular to the face of the coil. If the magnetic flux in the coil set to zero within 2 ms. What is the magnitude of the
  • 2014 E.C., Q14 – According to the law of electromagnetic induction,
  • 2013 E.C., Q6 – A coiled copper has 50 turns and coil cross-sectional area of 9 x10^-4m²? This coil is initially placed in a uniform magnetic field 0.02 T and pulled out of a field completely (where the field is zero) in 0.5 seconds. Wh
  • 2011 E.C., Q41 – A rectangular loop of area is placed in a magnetic field that is changing at a rate of 100T/s. If the normal 60∘ of the loop makes angle with the magnetic field, what is the magnitude of induced emf?
  • 2011 E.C., Q40 – Lenz's law in electromagnetic induction follows from which law of conservation ?
  • 2010 E.C., Q35 – An inductor has a self inductance of $12\,\text{mH}$. The current in the circuit decreases at a rate of $2.0\,\text{A/s}$. what is the magnitude of the induced electromotive force?
  • 2008 E.C., Q37 – Which conversion process forms the bases for the function of an electric generator?
  • 2008 E.C., Q38 – What is the change in magnetic flux in a coil of area as its orientation relative to the perpendicular of 45∘ 90∘ uniform 3.0T magnetic field changes from to ?
  • 2006 E.C., Q34 – A coil formed by wrapping 50 turns of wire in the shape of a square is positioned in a magnetic field so that the 37∘ normal to the plane of the coil makes an angle with the direction of the field. When the magnetic fiel
  • 2005 E.C., Q6 – On which of the following does the induced emf in a coil NOT depend when a magnet is inserted into it?
  • 2005 E.C., Q26 – Which devices uses the principle of electromagnetic induction for its operation?