Social networks

OpenProf

Unlock access to content

Select one option:

Free of charge

Unlock the chapter "The Magnetic Effect of a Current"

Unlock access to the solution of problems in this chapter.
Free of charge Price: 3.00 £

Continue »

Subscribe to OpenProf If you do not get a better grade, you get your money back!

Unlock access to all problems solutions.
Available from 8.25 £ / month.

Continue »

physics Physics For High Schools (KS4)

Solved problems for the chapter:

The Magnetic Effect of a Current

View the theory »

Magnetic Force on a Current-Carrying Conductor

1. Force on a current-carrying conductor in a magnetic field

2. Forum

↓ Show theory [1] ↓

Detailed solution steps are available at:

https://en.openprof.com/wb/chapter:the_magnetic_effect_of_a_current/3651/

Example 1.

There is a current in a wire. The wire is carrying current out of the page. Which diagram shows the pattern of the magnetic field produced?

Example 2.

The diagram shows a conductor carrying current out of the plane of the page. Which set of arrows represents the direction of the magnetic field due to this current?

The diagram shows the magnetic field due to a current in a solenoid. Where is the magnetic field the strongest?

A current in a solenoid produces a uniform magnetic field inside the solenoid. The magnetic field direction is due east. Which changes will produce a stronger magnetic field with a direction due west?

Use a smaller current and reverse the current.
Use a larger current and turn the solenoid through
Use a smaller current and turn the solenoid through
Use a larger current and reverse the current.

The diagram shows the magnetic field due to a current in a solenoid.

The direction of the current is reversed. Which row describes the effect that this has on the magnitude and on the direction of the magnetic field?

	magnitude of magnetic field	direction of magnetic field
A	unchanged	changes
B	increases	unchanged
C	unchanged	unchanged
D	increases	changes

Which device relies upon the magnetic effect of an electric current?

thermistor
fuse
variable resistor
relay

Which diagram represents the strength and direction of the magnetic field around a current-carrying conductor? The direction of the current is into the page.

The diagram shows part of a long current-carrying conductor. At which point is the magnetic field strongest?

Three statements about a relay are given.

A relay has a coil that becomes a temporary magnet when in operation.
A large current in a relay coil is used to switch off a smaller current.
A small current in a relay coil is used to switch on a larger current.

Which statements are correct?

1 and 2 only
2 and 3 only
1 and 3 only
1, 2 and 3

10.

In an experiment, a wire is held above a compass needle as shown.

An electric current is switched on in the wire and the compass is deflected. Which row explains why this happens and what happens when the current is reversed?

	why this happens	what happens when the current is reversed
A	there is a magnetic field inside the wire	the compass needle deflects in the opposite direction
B	there is a magnetic field inside the wire	the compass needle remains deflected in the same direction
C	there is a magnetic field around the wire	the compass needle deflects in the opposite direction
D	there is a magnetic field around the wire	the compass needle remains deflected in the same direction

11.

Four appliances all use an electric current to operate. Which appliance uses the magnetic effect of the current?

a remote controller
a heater
a relay
a light bulb

12.

In which device is the magnetic effect of a current not used?

potential divider
electromagnet
relay
loudspeaker

13.

A straight wire is perpendicular to the paper. It carries a current into the paper. What is the magnetic field pattern and its direction near the wire?

14.

A solenoid is connected to a battery. Which statement about the magnetic field at the centre of the solenoid is correct?

The direction of the magnetic field is perpendicular to the axis
The direction of the magnetic field is parallel to the axis
The magnetic field along the axis is zero
The direction of the magnetic field is at angle of to the axis

15.

The diagram represents a magnetic field. What causes this field?

two north poles close together
a solenoid carrying current
bar magnet
a straight wire carrying current

16.

There is an electric current in a straight wire in the direction into the page. This produces a magnetic field around the wire. All the field lines are circles but only one field line is shown.

Which row describes the magnetic field?

	direction of the field lines	spacing of the field lines
A	anti-clockwise	evenly spaced over the whole field
B	anti-clockwise	more widely spaced further from the wire
C	clockwise	evenly spaced over the whole field
D	clockwise	more widely spaced further from the wire

17.

An electric current can produce a heating effect and a magnetic effect. Which row shows the effect that a relay uses and one application of a relay?

	effect used by a relay	one application of a relay
A	heating effect	allowing a small current to switch on a large current
B	heating effect	changing the voltage of an a.c. supply
C	magnetic effect	allowing a small current to switch on a large current
D	magnetic effect	changing the voltage of an a.c. supply

18.

A strong electromagnet is used to attract pins. What happens when the current in the coil is halved?

Some pins are attracted, but not as many.
More pins are attracted.
No pins are attracted.
The same number of pins is attracted.

19.

A straight current-carrying wire has a magnetic field around it. Which diagram best shows the magnetic field pattern around the wire?

20.

Which diagram shows the pattern and direction of the magnetic field due to a current in a straight wire?