Magnetic effect of a current

The diagram illustrates the magnetic field pattern produced by a current in a solenoid. If the current in the solenoid is increased, at which position does the magnetic field strength increase?

May/June 2015

Fig. 10.1 depicts a relay linked to a cell and a switch. The diagram identifies the coil, iron core, iron armature, pivot, and terminals A, B, C and D.

May/June 2015

In a wire, an electric current is directed into the page. Which diagram illustrates the pattern and direction of the magnetic field surrounding the wire?

May/June 2018

A steel rod is magnetised by means of an electrical technique.

May/June 2018

Two vertical wires run through a piece of card at right angles. Each wire carries a large current in the direction indicated. A plotting compass is placed on the card. Which diagram shows the direction in which the needle of the plotting compass points?

May/June 2019

What material is used for the core of an electromagnet?

May/June 2022

The diagram depicts the magnetic field that surrounds wire X, with the current flowing into the paper. The arrows on the field lines indicate the direction of the force acting on

Oct/Nov 2015

Two flexible iron strips, WX and YZ, are positioned close together inside a solenoid (long coil). The end W of WX and the end Z of YZ are fixed firmly in place. Fig. 6.1 shows the solenoid connected to a d.c. power supply and a switch. When the switch is closed, an electric current flows in the solenoid. End W of flexible iron strip WX becomes a magnetic S-pole.

Oct/Nov 2016

Inside a cathode-ray oscilloscope (c.r.o.), an electron beam is generated by a filament at one end of an evacuated glass tube. The electrons are then accelerated and hit a screen at the opposite end of the tube.

Oct/Nov 2016

A vertical solenoid (long coil) containing an iron core is clamped in a wooden holder above a laboratory bench. The solenoid is joined in series to a battery, a switch S, an ammeter and a variable resistor. A voltmeter is connected across the solenoid in parallel.

Oct/Nov 2016

Why is the coil in an electric motor wrapped around a soft-iron cylinder?

Oct/Nov 2017

A straight wire carries a current into the paper. The diagram shows three magnetic field lines surrounding the wire. The current in the wire increases. What is the direction of the field lines, and what change happens to the field lines as the current increases?

Oct/Nov 2017

The diagram illustrates an alarm system with switch S closed. The upper circuit is set up so that the electromagnet sits above the soft iron contact. What occurs when switch S is opened?

Oct/Nov 2021

The diagram illustrates an alarm system with switch S shown in the closed position. The upper circuit is set up so that the electromagnet is located above the soft iron contact. What occurs when switch S is opened?

Oct/Nov 2021

An electron beam is directed into a uniform magnetic field, as illustrated. The magnetic field points into the page. Which route do the electrons take?

Oct/Nov 2022

The diagram illustrates a relay used to turn on an electric motor. A student writes five statements to describe how the relay turns on the electric motor. The statements are not arranged in the correct sequence. What is the correct order of the statements?

Oct/Nov 2022

Which device makes use of the magnetic effect produced by an electric current?

Oct/Nov 2023

Students are required to sketch the pattern and direction of the magnetic field produced by a direct current (d.c.) in a straight wire. Diagrams 1, 2 and 3 are three of the answers they gave. The students do not know which way the current flows in the wire. Which diagrams show patterns and directions that could be correct for the magnetic field produced by the current in the wire?

Oct/Nov 2024

A current flows through a straight vertical wire in the direction indicated. What pattern is formed by the magnetic field around the wire for an observer looking at the wire from the position shown?

Oct/Nov 2024