Forces on a current-carrying conductor

The diagram illustrates a wire PQ positioned between the N-pole and the S-pole of a magnet. A current flows in the wire in the direction shown by the arrow. In which direction does the force act on wire PQ?

May/June 2016

Fig. 7.1 shows a section of a loudspeaker. A coil is fixed to a paper cone and hangs freely inside a cylindrical magnet.

May/June 2016

A horizontal beam of electrons travels between the two poles of a magnet. Which direction does the beam deflect?

May/June 2018

A beam of electrons moves through a vacuum. As shown, the beam passes between the poles of a magnet. State the direction of the conventional current and the direction of the magnetic field.

May/June 2019

Fig. 7.1 shows a copper wire resting on two copper rods in the magnetic field between the poles of a magnet. Crocodile clip A is in contact with the positive terminal of the battery. As a result, the copper wire starts to move.

May/June 2019

An illustrated horizontal rectangular wire coil WXYZ is placed between the poles of a magnet. A current flows through the coil in the direction indicated. Which statement is correct?

May/June 2021

The diagram shows a current-carrying conductor placed between the poles of a magnet, and the force on the wire is downward. Four possible changes are given. Which pair of changes, if applied together, still makes the force act downwards?

May/June 2021

The diagram shows a beam of electrons just before it moves into a magnetic field. The magnetic field points into the page. In which direction are the electrons deflected as they enter the magnetic field?

May/June 2022

A left hand can be used to determine the direction of the force when a current-carrying conductor is at right angles to a magnetic field. Which quantities are indicated by the directions of fingers P, Q and R?

May/June 2022

The diagram illustrates a wire carrying a current in a magnetic field. In which direction does the force act on the wire?

May/June 2024

Fig. 6.1 illustrates the arrangement of a basic electric motor. As current passes through the coil, the coil begins to rotate. A student sees that the coil moves in the direction indicated by the curved arrow in Fig. 6.1.

May/June 2024

A beam of beta particles moving vertically downward enters the magnetic field between two magnetic poles. The beta particles experience a force because of the magnetic field. What is the direction of the force on a beta particle as it enters the magnetic field?

May/June 2025

P and Q are two parallel straight wires with currents directed into the plane of the paper. P and Q act on each other with a force. Which arrow indicates the force acting on Q?

Oct/Nov 2015

P and Q are two parallel, straight wires carrying currents into the plane of the paper. P and Q act on each other with a force. Which arrow indicates the force acting on Q?

Oct/Nov 2015

A wire carrying a current is positioned between the poles of two magnets, as illustrated. In which direction does the force act on the wire?

Oct/Nov 2016

A coil P with $N$ turns is formed from a wire length of $L$. When it is placed between two magnetic poles, the coil carries a current $I$. A comparable coil Q with $2N$ turns is formed from a wire length of $2L$ of the same wire. It also carries a current $I$ when it is placed between the same magnetic poles. Which coil has the larger resistance, and which coil undergoes the larger turning effect?

Oct/Nov 2016

A current-carrying wire is placed between the poles of two magnets, as illustrated. In which direction does the force act on the wire?

Oct/Nov 2016

An electric circuit is made up of a battery, a variable resistor and connecting wires. The sections PQ and QR of the connecting wire lie in a part of space with a uniform magnetic field. In Fig. 7.1, the shaded region shows the magnetic field.

Oct/Nov 2017

A wire is positioned in the magnetic field between the poles of a magnet, as illustrated. When current flows through the wire, a force acts on it. Which change would make this force larger?

Oct/Nov 2018

Fig. 7.1 illustrates a rectangular coil ABCD lying horizontally between an N-pole and an S-pole. A current flows through the coil. Side AB is acted on by an upward force F of magnitude $9.6 \times 10^{-3}\,\text{N}$.

Oct/Nov 2019

The electric circuit is powered by a battery with electromotive force (e.m.f.) 12 V.

Oct/Nov 2022

A wire is positioned at right angles to a uniform magnetic field. A current flows through the wire, so it experiences a force. Beams of alpha-particles, beta-particles and neutrons are directed into the magnetic field in the same direction as the conventional current in the wire. Which beams experience a force that is initially in the same direction as the force on the current-carrying wire?

Oct/Nov 2023

Two current-carrying conductors are positioned close together. The current in both conductors flows in the same direction. Which statement about the forces acting on the conductors is correct?

Oct/Nov 2025