# Absence of m.field around an AC current carrying wire

• waqarrashid33
In summary, the absence of magnetic field around an AC current carrying wire occurs because the magnetic field created by the alternating current in the wire cancels out due to its changing direction. This is due to the principle of superposition, which states that when two or more magnetic fields interact, their effects cancel out or add together. However, this is not always true and only applies to infinitely long, straight wires with constant alternating current. This phenomenon has important implications for electromagnetic induction and can also have a shielding effect on the wire's surroundings.
waqarrashid33
One of my friend says that it is possible that there will be no magnetic filed around an AC current carrying wire but he did,t know about the reason. can anyone give the reason

There is always a magnetic field around a single wire carrying a current, either AC or DC. Use Ampere's Law to calculate. If it is a pair of wires in close proximity (like a two-wire lamp cord), with one wire carrying a return current, the magnetic field is minimal.

Bob S

## 1. What is the absence of magnetic field around an AC current carrying wire?

The absence of magnetic field around an AC current carrying wire refers to the fact that there is no magnetic field present in the space immediately surrounding the wire. This phenomenon occurs because the magnetic field created by the alternating current in the wire cancels out due to its changing direction.

## 2. Why is there no magnetic field around an AC current carrying wire?

The absence of magnetic field around an AC current carrying wire is due to the principle of superposition. This means that when two or more magnetic fields interact, their effects cancel out or add together. In the case of an AC current carrying wire, the magnetic field created by the alternating current in the wire cancels out, resulting in no net magnetic field.

## 3. Is the absence of magnetic field around an AC current carrying wire always true?

No, the absence of magnetic field around an AC current carrying wire is not always true. It only applies in the case of an infinitely long, straight wire with a constant alternating current. In other situations, such as a non-straight wire or a wire with a varying current, there may be a magnetic field present around the wire.

## 4. What are the implications of the absence of magnetic field around an AC current carrying wire?

The absence of magnetic field around an AC current carrying wire has important implications for electromagnetic induction. Since there is no magnetic field present, there can be no induced current in nearby conductors. This is why power lines, which carry AC current, do not cause interference with nearby telephone or cable lines.

## 5. How does the absence of magnetic field around an AC current carrying wire affect the wire's surroundings?

The absence of magnetic field around an AC current carrying wire can have a shielding effect on its surroundings. This means that objects or materials placed near the wire may be protected from external magnetic fields. This property is utilized in the design of MRI machines, which use superconducting wires to create a strong magnetic field that shields the patient from external magnetic fields.

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