Question:

A solenoid of inductance $2H$ carries a current of $1A$. What is the magnetic energy stored in a solenoid ?

Updated On: Feb 23, 2024
  • 2 J
  • 1 J
  • 4 J
  • 5 J
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The Correct Option is B

Solution and Explanation

By energy stored in an inductor $U=\frac{1}{2} L i_{0}^{2}$ ($L=$ inductance of inductor, $i_{0}=$ current) where $L=2 H,\, i_{0}=1\, A$ $U=\frac{1}{2} \times 2 \times 1^{2}=1\, J$
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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.