CBSE · Class 10 · Science · Magnetic Effects of Electric CurrentA long straight wire carries a current of $10\text{ A}$. Calculate the magnitude of the magnetic field produced at a perpendicular distance of $5\text{ cm}$ from the wire. Given the permeability of free space $\mu0 = 4\pi \times 10^{-7} \text{ T}\cdot\text{m/A}$. Also, state the rule used to find the direction of this magnetic field and explain it briefly.
Step-by-Step Solution
Given Data:
- Current ($I$) = $10\text{ A}$
- Distance ($r$) = $5\text{ cm} = 5 \times 10^{-2} \text{ m}$
- Permeability of free space ($\mu_0$) = $4\pi \times 10^{-7} \text{ T}\cdot\text{m/A}$
Formula:\nThe magnetic field ($B$) at a perpendicular distance $r$ from a long straight current-carrying wire is given by:
$$B = \frac{\mu_0 I}{2\pi r}$|
Calculation:\nSubstitute the given values into the formula:
$$B = \frac{(4\pi \times 10^{-7} \text{ T}\cdot\text{m/A}) \times (10 \text{ A})}{2\pi \times (5 \times 10^{-2} \text{ m})}|$$ \nSimplify the expression: $$B = \frac{4\pi \times 10^{-6}}{10\pi \times 10^{-2}}$$ $$B = \frac{4\pi \times 10^{-6}}{\pi \times 10^{-1}}$$ $$B = 4 \times 10^{-6 - (-1)} \text{ T}$$ $$B = 4 \times 10^{-5} \text{ Tesla} (\text{or } 40 \mu\text{T})$|
Direction of Magnetic Field:\nTo find the direction of the magnetic field produced by a straight current-carrying wire, we use Maxwell's Right-Hand Thumb Rule (also known as the Right-Handed Screw Rule).
Statement of Maxwell's Right-Hand Thumb Rule:\nImagine that you are holding a current-carrying straight wire in your right hand such that your thumb points in the direction of the current. Then your fingers will wrap around the wire in the direction of the field lines of the magnetic field.
💡 Study Guide: This question tests core syllabus concepts from Magnetic Effects of Electric Current. For formulas, key summaries, and mock exam reference guides, read the full Magnetic Effects of Electric Current Revision Notes.