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Q1 A piece of iron and a piece of steel are picked up by an electromagnet as shown. The current to the electromagnet is switched off. What happens?

Q2 A permanent magnet is brought near to a piece of copper. The copper is not attracted by the magnet. Why is there no attraction?

Q3 Which row describes the ease with which iron or steel can be magnetised and demagnetised?

Q4 An electromagnet is used to separate magnetic metals from non-magnetic metals. Why is steel unsuitable as the core of the electromagnet?

Q5 Four substances are tested by using each as the core of an electromagnet. The number of paper clips held is recorded when there is a current in the electromagnet and when the current is switched off. Which substance is the best for the core?

Q6 Four metal rods are placed, in turn, inside a coil of copper wire. The table below gives the results of the experiment. Which rod would be the most suitable to use for the core of a coil in a circuit breaker?

Q6 explanation

Q7 In order to produce a magnetic field, an electric charge must be

Q8 Which type of field is present near a moving electric charge?

Q9 The magnetic lines of force near a long straight current-carrying wire are

Q10 A straight wire carrying a current produces a magnetic field. Which diagram shows the correct shape of the field?

Q11 What can be deducted from the following diagram showing a current flowing in a straight wire surrounded by 4 compasses?

Q12 Plotting compasses X and Y are placed below and top of a current carrying wire respectively as shown in the diagram. Which of the following shows the current compass pointers’ directions?

Q13 Plotting compasses X and Y are placed on the right and on the left of a current carrying wire respectively as shown in the diagram. In which directions will the compass needles point?

Q14 Which diagram best represents the magnetic field around a straight wire in which electrons are flowing from left to right?

Q14 explanation

Q15 The diagram below represents the magnetic field around point P, at the center of a current carrying wire. What is the direction of electron flow in the wire?

Q16 Which diagram best represents the direction of the magnetic field around a wire conductor in which the electrons are moving as indicated?

Q17 Conventional current is flowing southward in a power line. The geographic direction of the magnetic field under the power line is

Q18 Equal amount of current is flowing in two insulated wires perpendicular to each other as shown. Which segment, A, B, C or D has the strongest magnetic field flowing out of the paper?

Q19 Equal amount of current is flowing in two insulated wires perpendicular to each other as shown. Which segment, A, B, C or D has the strongest magnetic field flowing out of the paper?

Q20 The diagram below shows an electron current in a wire loop. What is the direction of the magnetic field at the center of the loop?

Q20 explanation

Q21 In the diagram below A, B, C, and D are points in the magnetic field near a current carrying loop. At which points is the direction of the magnetic field into the page?

Q22 A long wire that carries a current I is bent into five loops as shown in the figure. If the observer could "see" the magnetic field inside this arrangement of loops, how would it appear?

Q23 A current in a solenoid creates a magnetic field. What is the effect on the magnetic field at the point P of using a larger current in the opposite direction?

Q24 In the diagram, in which direction is the magnetic field at point X?

Q25 The diagram below shows an electromagnet made from a nail, a coil of insulated wire, and a battery. The south pole of the electromagnet is located closest to point

Q26 The diagram below shows a coil of wire (solenoid) connected to a battery. The north pole of a compass placed at point P would be directed toward point

Q27 A current-carrying solenoid is placed with its axis pointing east-west. A small compass is situated near one end of the solenoid. The current in the solenoid is doubled. Which of the following best shows the new position of the compass needle?

Q28 A wire is coiled around an iron bar and connected to a 12 V battery When current flows in the wire, what are the poles attained by X, Y and Z respectively?

Q29 The diagram below shows a small magnet hanging on a thread near to the end of a solenoid carrying a steady current I. What will happen to the magnet as the iron core is inserted into the solenoid?

Q30 Two solenoids are wound on soft iron cores and connected to batteries, as shown in the diagram below. When switches S1 and S2 are closed, the solenoids

Q31 In the below, the current to both solenoids are turned on, they will________________.

Q32 Two solenoids, X and Y, are connected in series as shown and are suspended near each other. When X and Y are connected to an a.c. supply, they will

Q33 The diagram below represents a solenoid in which there is no electric current. Which one of the following best represents the magnetic field pattern due to an electric current in the solenoid?

Q34 The diagram shows an alarm system in which the switch S is shown closed. What happens when the switch S is opened?

Q35 The circuit contains a relay. When switch S is closed, what is the state of the lamps?

Q36 The diagram shows parts of a loudspeaker. Which type of current is passed through the coil and why?

Q37 An iron-cored electromagnet is to be used in a relay to switch off a high current by attracting a flexible iron strip as shown. It is found that the relay does not operate properly. Which of the following changes might make it work?

Q38 'Perpetual Swing’ is a toy consisting of a suspended permanent magnet that keeps on swinging.

Q39 The figure below shows an upwards force acting on a current-carrying wire. What is the direction of the magnetic field?

Q40 The diagram below shows a U-shaped wire hanging freely in rods X and Y. Rods X and Y are connected to a d.c. supply. Which of the following is true?

Q41 In the diagram below, a wire carrying an electron current into the page, as denoted by X, is placed in a magnetic field. The magnetic field exerts a force on the wire toward point____.

Q42 In the diagram at the right, when the negative current is flowing in the direction indicated by the arrow, the direction of the force in the wire will be

Q43 In the diagram below, a wire is suspended in the presence of a magnetic field. As electrons begin to flow through the wire as indicated, in which direction will the wire tend to move?

Q44 In the diagram at the right, electrons flowing through the wire as shown will cause the wire to move toward the

Q45 A wire carrying an electron current (e–) is placed between the poles of a magnet, as shown in the diagram below. Which arrow represents the direction of the magnetic force on the current?

Q46 The diagram at the right represents a conductor carrying an electron current in magnetic field B. The direction of the magnetic force on the conductor is

Q47 When the electric current in wire XY is in the direction shown, there is an upward force on the wire. If the north and south poles of the magnet exchange positions, in which direction will the force on the wire act?

Q48 A strip of aluminium foil is held between the poles of a strong magnet, as shown below. When a current is passed through the aluminium foil in the direction shown, the foil is deflected. In which direction is this deflection?

Q49 A current-carrying wire is placed between two magnets as shown below. What is the direction of force acting on the wire?

Q50 A current-carrying wire is placed between two magnets as shown below. What is the direction of force acting on the wire?

Q51 A current is made to pass through a swing mounted to the ceiling such that it can swing freely. The swing will

Q52 When the switch in the circuit shown is closed, the bare wire XY will

Q53 Two current-carrying wires (P and Q) are placed between two magnets and their currents are equal but in opposite directions as shown below. What are the directions of forces acting on the wires?

Q54 An a.c. supply is connected to a wire stretched between the poles of a magnet. Which way will the wire move?

Q55 A copper wire is held between the poles of a magnet. The current in the wire can be reversed. The poles of the magnet can also be changed over. In how many of the four directions shown can the force act on the wire?

Q56 Four current-carrying wires are placed between two magnets as shown in the plan view below. Which wire would experience the smallest electromagnetic force?

Q57 A wire carrying a direct current is held above a magnet as shown in the diagram. The resultant magnetic field of the magnet and the wire interact with each other and the current will cause the wire to experience a force in the direction____.

Q58 In the diagram below Q is a circular coil of wire carrying a clockwise current I. P is a long, straight wire carrying a current perpendicularly into the page through the centre of the coil. Each part of Q will experience_____________________.

Q59 Four long straight parallel wires carry equal currents directed vertically out of the page. They are arranged on the corners of a square as shown in the figure below. The direction of the resultant magnetic force exerted on the wire labelled X is

Q60 The diagram shows a rectangular wire frame balanced on knife edges. One side of the wire frame rests on an electronic balance, while part of the other side lies in a magnetic field. What could be done to obtain a smaller reading on the mass balance?

Q61 A bar magnet is fixed in a container of mercury as shown. A copper wire PQ is connected to a cell and freely suspended at P. What will happen to the end Q, as seen by the observer, when the switch is closed and remains closed?

Q62 A magnetic force acts on an electric charge in a magnetic field when

Q63 A particle is being accelerated by a magnetic field. This particle must be

Q64 A charged particle is moving with a constant velocity. On entering a uniform magnetic field, the particle

Q65 An electron and a proton travelling with the same velocity are injected into a region of uniform magnetic field at 90° to the magnetic field direction. The initial magnetic forces on them are

Q66 A charged particle is situated in a region of space and it experiences a force only when it is in motion. It can be deduced that the region encloses _________________.

Q67 The diagram below shows electron e about to enter the region between the poles of two magnets. Upon entering the region between the poles, the moving electron will experience a magnetic force directed

Q68 Hot air from a hair-dryer contains many positively charged ions. The motion of these ions constitutes an electric current. The hot air is directed between the poles of a strong magnet, as shown. What happens to the ions? They are deflected

Q69 Upon entering the magnetic field, the negatively charged particles will be deflected

Q70 An electron traveling at a speed (V) in the plane of this paper enters a uniform magnetic field. Which diagram best represents the condition under which the electron will experience the greatest magnetic force as it enters the magnetic field?

Q71 A proton enters a region of magnetic field as shown below. The proton will

Q72 The diagram shows a beam of electrons entering a magnetic field. The direction of the field is into the page. In which direction are the electrons deflected?

Q73 The diagram shows a beam of electrons entering a magnetic field. What is the effect of the magnetic field on the electrons?

Q74 In the diagram below, a free electron is traveling upward parallel to a conductor. Electrons begin to flow upward in the conductor. Which diagram best represents the resulting magnetic field and the direction of the magnetic force on the electron?

Q75 A positively charged particle enters a uniform magnetic field. The particle’s velocity is parallel to the magnetic field. Which of the following correctly shows the path of the charged particle while in the magnetic field?

Q76 A charged particle is injected into a region of uniform magnetic field and travels in a circular arc. If the particle were to be injected with a greater speed, what would be true of the magnetic force on it and the radius of its path?

Q77 An electron traveling at a speed (V) in the plane of this paper enters a uniform magnetic field. Which diagram best represents the condition under which the electron will experience the greatest magnetic force as it enters the magnetic field?

Q78 A beam of electrons is moving through a uniform magnetic field perpendicular to the field. Which graph shows how the magnetic force varies as the speed of the electrons is increased?

Q79 A plotting compass is placed beside a current-carrying wire as shown below. Given that the current flowing through both wires has the same magnitude, which of the following shows the correct direction of the plotting compass?

Q80 A plotting compass is placed in between two current-carrying wires as shown below. Given that the current flowing through both wires has the same magnitude, which of the following shows the correct direction of the plotting compass?

Q81 X and Y are wires carrying electric currents at right angles to the page. P, Q and R are plotting compasses. Any effect of the Earth’s magnetic field has been ignored. What is true about the direction and size of the currents?

Q82 Each diagram shows a cross-section of two parallel conductors, each carrying an electric current. Which diagram shows the directions of the forces on the conductors?

Q83 Two current-carrying wires are arranged in parallel as shown below. What is the direction of the electromagnetic force on each wire?

Q84 Two current-carrying wires are arranged in parallel as shown below. What is the direction of the electromagnetic force on each wire?

Q83 and Q84 explanation

Q85 Two parallel vertical wires P and Q are a small distance apart in air. There is a downwards electric current in both wires. What is the direction of the force on Q?

Q86 In the diagram below, what are the directions of the electromagnetic forces acting on wire X and wire Y?

Q87 Which of the following currently identifies the motion of the wires and the compasses that point in the same direction?

Q88 Each of the diagrams is a cross-section through two parallel, current-carrying conductors. Which diagram shows correctly the magnetic field pattern and the directions of the forces on the two conductors?

Q89 A long flexible wire is wrapped round two wooden pegs. A large current is passed in the direction shown. Which two pairs of lengths of wire attract each other?

Q90 The diagram below shows three parallel wires P, Q and R that are equally spaced. The currents in the wires are each of the same magnitude I and are in the directions shown. The resultant force on wire Q due to the current in wire P and in wire R is

Q90 explanation

Q91 A long straight wire XY lies in the same plane as a square loop of wire PQRS which is free to move. PS and QR are initially parallel to XY. The wire and loop carry steady currents as shown in the diagram. What will be the effect on the loop?

Q92 What does not alter the size of the turning effect on the coil of an electric motor?

Q93 A coil, carrying a current, is arranged within a magnetic field. The coil experiences forces that can make it move. In which direction does the coil move?

Q94 The diagram shows a coil in a magnetic field. When the coil is part of a d.c. motor, what must be connected directly to X and Y?

Q95 A d.c. motor consists of a coil rotating in a fixed magnetic field. The coil is connected to a d.c. supply through a split-ring commutator. Some changes are made, one at a time. How many of these changes make the coil rotate in the opposite direction?

Q96 A simple model of a d.c. motor is made. By mistake, the split-ring commutator is left out. The coil can turn, but is always connected to the battery in the same way. What happens to the coil when the circuit is switched on?

Q97 The diagram shows a d.c. motor. Why is a split-ring commutator used?

Q98 The diagram shows a coil of wire that can rotate between the poles of a magnet. What is the position of the coil in the magnetic field so that its turning effect is a maximum and what is the position of the coil when the current is reversed?

Q99 A direct current (dc) motor is connected to a battery by means of two leads. What is the function of the commutator of the motor?

Q100 The function of the split-ring commutator in a simple direct-current (d.c.) motor is to reverse the direction of the current....?

Q101 The function of the commutator of a d.c. electric motor is

Q102 In a d.c. motor, the coil is wound on a soft iron cylinder. Why is soft iron used?

Q103 The core of a d.c. motor is usually made of soft iron because soft iron

SQ1 (part 1) Coil with flexible leads forces on the coil

SQ1 (part 2) Coil with flexible leads drawing the split-ring commutator

SQ2 Wire through horizontal board

SQ3 Circuit-breaker

SQ4 (part 1) Force on a current-carrying conductor Fleming's left-hand rule

SQ4 (part 2) Force on a current-carrying conductor coil in a magnetic field

SQ5 Circuit-breaker 2

SQ6 Electric bell

SQ7 Combined magnetic field of wire and bar magnets

SQ8 Positive charge in magnetic field

SQ9 DC motor

SQ10 Rotating coil

SQ11 (part 1) Magnetic recording tape polarity and current

SQ11 (part 2) Magnetic recording tape changing the setup

SQ12 Loudspeaker

SQ13 Solenoid magnetic field

SQ14 Relay

SQ15 (part 1) Electric bell relay explaining why the bell rings

SQ15 (part 2) Electric bell relay circuit calculations

SQ16 (part 1) Two wires through a card drawing the magnetic fields

SQ16 (part 2) Two wires through a card the force on wire Y

SQ17 (part 1) Mercury tray experiment drawing arrows

SQ17 (part 2) Mercury tray experiment changes that increase the force

SQ18 (part 1) 6V battery with 3 metal rods drawing arrows

SQ18 (part 1) 6V battery with 3 metal rods explain alternating current

SQ19 Magnetic field between 2 poles

SQ20 Force on a current-carrying conductor 2

SQ21 (part 1) Magnetic field in a coil drawing the field

SQ21 (part 2) Magnetic field in a coil electromagnet material

SQ22 Aluminium rod in horseshoe magnet

SQ23 Horseshoe magnet on weighing balance

SQ24 Steel wire attached via pulley to a weight

SQ25 Nail electromagnet

SQ26 (part 1) Magnetic fields tick the box

SQ26 (part 2) Magnetic fields force on the rod