Question:
The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2r is
The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2r is
Updated On: Apr 15, 2024
- 0.2 tesla
- 0.8 tesla
- 0.1 tesla
- 0.6 tesla
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The Correct Option is A
Solution and Explanation
Magnetic field due to long wire,
$B=\frac{\mu_{0}i}{2\pi r}$ or $B\,\propto\frac{1}{r}$
When $r$ is doubled, the magnetic field becomes half, i.e., now the magnetic field will be $0.2\, T$.
$B=\frac{\mu_{0}i}{2\pi r}$ or $B\,\propto\frac{1}{r}$
When $r$ is doubled, the magnetic field becomes half, i.e., now the magnetic field will be $0.2\, T$.
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Concepts Used:
Magnetic Field
The magnetic field is a field created by moving electric charges. It is a force field that exerts a force on materials such as iron when they are placed in its vicinity. Magnetic fields do not require a medium to propagate; they can even propagate in a vacuum. Magnetic field also referred to as a vector field, describes the magnetic influence on moving electric charges, magnetic materials, and electric currents.
A magnetic field can be presented in two ways.
- Magnetic Field Vector: The magnetic field is described mathematically as a vector field. This vector field can be plotted directly as a set of many vectors drawn on a grid. Each vector points in the direction that a compass would point and has length dependent on the strength of the magnetic force.
- Magnetic Field Lines: An alternative way to represent the information contained within a vector field is with the use of field lines. Here we dispense with the grid pattern and connect the vectors with smooth lines.
Properties of Magnetic Field Lines
- Magnetic field lines never cross each other
- The density of the field lines indicates the strength of the field
- Magnetic field lines always make closed-loops
- Magnetic field lines always emerge or start from the north pole and terminate at the south pole.