Question:
A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the line?
A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the line?
Updated On: Sep 29, 2023
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Solution and Explanation
Current in the power line, \(I\) = 90
A Point is located below the power line at distance, \(r\) = 1.5 m
Hence, magnetic field at that point is given by the relation,
\(|B|= \frac{μ_0}{4π}. \frac{2l}{r}\)
Where,
\(μ_0\) = Permeability of free space
\(= 4π × 10^{–7} T\,m \,A^{–1}\)
\(|B| =\frac{4π × 10^{–7}}{4π} × \frac{2 × 90}{1.5 }\)
\(= 1.2 × 10^{-5} T\)
The current is flowing from East to West. The point is below the power line. Hence, according to Maxwell’s right hand thumb rule, the direction of the magnetic field is towards the South.
A Point is located below the power line at distance, \(r\) = 1.5 m
Hence, magnetic field at that point is given by the relation,
\(|B|= \frac{μ_0}{4π}. \frac{2l}{r}\)
Where,
\(μ_0\) = Permeability of free space
\(= 4π × 10^{–7} T\,m \,A^{–1}\)
\(|B| =\frac{4π × 10^{–7}}{4π} × \frac{2 × 90}{1.5 }\)
\(= 1.2 × 10^{-5} T\)
The current is flowing from East to West. The point is below the power line. Hence, according to Maxwell’s right hand thumb rule, the direction of the magnetic field is towards the South.
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Concepts Used:
Biot Savart Law
Biot-Savart’s law is an equation that gives the magnetic field produced due to a current-carrying segment. This segment is taken as a vector quantity known as the current element. In other words, Biot-Savart Law states that if a current carrying conductor of length dl produces a magnetic field dB, the force on another similar current-carrying conductor depends upon the size, orientation and length of the first current carrying element.
The equation of Biot-Savart law is given by,
\(dB = \frac{\mu_0}{4\pi} \frac{Idl sin \theta}{r^2}\)
Application of Biot Savart law
- Biot Savart law is used to evaluate magnetic response at the molecular or atomic level.
- It is used to assess the velocity in aerodynamic theory induced by the vortex line.
Importance of Biot-Savart Law
- Biot-Savart Law is exactly similar to Coulomb's law in electrostatics.
- Biot-Savart Law is relevant for very small conductors to carry current,
- For symmetrical current distribution, Biot-Savart Law is applicable.
For detailed derivation on Biot Savart Law, read more.