Introduction to Magnetic Effect of Current

A magnet is an object that attracts objects made of iron, cobalt, and nickel. A magnet comes to rest in a north-south direction when suspended freely. When current flows through a wire, it creates a magnetic field. This can be observed by the deflection of a compass needle placed near the wire. Winding the wire into a coil enhances this effect, creating an electromagnet, which is useful in various applications.

Properties of Magnet:

1. A free suspended magnet always points towards the north and south directions.
2. The pole of a magnet that points toward the north direction is called the north pole or north-seeking.
3. The pole of a magnet that points toward the south direction is called the south pole or south-seeking.
4. Like poles of magnets repel each other, while unlike poles of magnets attract each other.

1. Aim: To demonstrate that a magnetic field is produced around a wire when an electric current flows through it.

2. Requirements: An inside tray of a used matchbox, a small magnetic needle, long connecting wire, an electric cell, a plug key, a light bulb, and a bar magnet.

3. Procedure

• Place the magnetic needle inside the matchbox tray.
• Wind the wire around the tray several times and connect it to an electric circuit with a cell, plug key, and bulb.
• Mark the magnetic needle's initial position. Bring a bar magnet close to the needle and observe its movement.
• Close the plug key to let current flow; the bulb lights up, and the magnetic needle changes position.
• Open the plug key to stop the current; the needle returns to its original position.

Magnetic effect of current

3. Conclusion: When the current flows through the wire, the magnetic needle changes direction, indicating that a magnetic field is created around the wire. When the current stops, the magnetic needle returns to its original position. This experiment shows that electric current produces a magnetic field, a phenomenon first observed by Hans Christian Oersted.

1. Aim: To observe the magnetic effect of electric current and its relation to the deflection of a magnetic needle.

2. Requirements: battery, plug key, thick copper wire, connecting wires, magnetic needle.

3. Procedure

• Connect the circuit as shown in the diagram.
• Place a magnetic needle near the copper wire between points A and B.
• Keep the plug key open (circuit OFF) and observe the needle’s position.
• Close the plug key (circuit ON) and note the deflection of the needle.
• Reverse the connections of the cell and observe the new direction of the needle’s deflection.

Magnetic effects of a current

4. Observation

• When the current flows through the wire, the magnetic needle deflects.
• Reversing the current changes the needle’s deflection direction.

5. Conclusion: Electric current creates a magnetic field around a conductor. The field’s direction depends on the current flow. This principle is the basis of electromagnetism, used in motors and generators.

1. Aim: To observe the magnetic field around a straight current-carrying conductor.

2. Requirements: battery, plug key, thick copper wire, cardboard, magnetic needle, iron filings.

3. Procedure

• Set up the circuit as shown in the diagram.
• Pass the thick copper wire vertically through the centre of the cardboard.
• Close the key to allow a large current (about 1A or more) to flow through the wire.
• Place a magnetic needle at different points around the wire and mark its directions.
• Spread iron filings on the cardboard and gently tap it to observe the pattern formed.

Magnetic field produced around the conductor

4. Observation

• The magnetic needle deflects in circular patterns around the wire.
• Iron filings arrange in concentric circles, showing magnetic field lines.
• The field strength decreases as the distance from the wire increases.
• Increasing the current strengthens the magnetic field.

5. Conclusion: A current-carrying conductor generates a magnetic field around it. The magnetic field forms concentric circles around the wire.

The field strength decreases with distance from the wire. Increasing the current increases the strength of the magnetic field. This experiment confirms that electricity and magnetism are interrelated, forming the basis of electromagnetism.

• Electric current creates a magnetic field, shown by compass needle deflection.
• Oersted discovered the link between electricity and magnetism in 1820.
• Reversing current changes the direction of the magnetic field.
• Iron filings form circular patterns, showing magnetic field lines around the wire.
• Magnetic field strength increases with current and decreases with distance.