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A magnetic field exists around a current-carrying conductor - Leaving Cert Physics - Question 9 - 2014
Question 9
A magnetic field exists around a current-carrying conductor. (i) What is a magnetic field? (ii) How does a compass indicate the direction of a magnetic field? (... show full transcript
Worked Solution & Example Answer:A magnetic field exists around a current-carrying conductor - Leaving Cert Physics - Question 9 - 2014
Step 1
What is a magnetic field?
Answer
A magnetic field is defined as the region or space around a magnet or current-carrying conductor where magnetic forces can be detected. It is a field that represents the magnetic influence on moving electric charges, magnetic dipoles, and electrical currents.
Step 2
How does a compass indicate the direction of a magnetic field?
Answer
A compass indicates the direction of a magnetic field by aligning its needle, which is a small magnet, with the field lines. The north pole of the compass needle points in the direction of the magnetic field lines, effectively showing the direction of the field.
Step 3
Describe an experiment to show that there is a magnetic field around a current-carrying conductor and sketch the field lines around the conductor.
Answer
To demonstrate that a magnetic field exists around a current-carrying conductor, set up a circuit with a power supply connected to a wire and a switch. When the switch is turned on, use iron filings spread on a piece of paper placed over the wire to visualize the magnetic field. The filings will align along circular paths around the wire, indicating the presence of a magnetic field. A sketch should illustrate these circular field lines around the conductor.
Step 4
Sketch the magnetic field around a bar magnet.
Answer
The magnetic field around a bar magnet can be represented with field lines emerging from the north pole (N) of the magnet, curving around, and entering the south pole (S). The lines should be drawn denser near the poles and more spaced out away from the magnet, indicating the strength of the field.
Step 5
What is observed when the magnet is moved towards the coil?
Answer
When the magnet is moved towards the coil, the galvanometer needle deflects, indicating the generation of an induced current in the coil. This deflection is due to the changing magnetic field through the coil caused by the movement of the magnet.
Step 6
Step 7
Explain these observations.
Answer
The observations can be explained using Faraday's law of electromagnetic induction, which states that a change in magnetic flux through a circuit induces an electromotive force (EMF) in the circuit. When the magnet is moved, the magnetic flux through the coil changes, inducing a current. Conversely, when the magnet is stationary, the magnetic flux remains constant, resulting in no induced current.
Step 8
How would increasing the speed of movement of the magnet alter the observations?
Answer
Increasing the speed of movement of the magnet would result in a greater change in magnetic flux through the coil over a given time period. This would lead to a larger induced current, which would cause a greater deflection of the galvanometer needle, indicating a stronger response due to the rapid change in the magnetic field.