A steady current is flowing in a power line from west to east.
The direction of the magnetic field at a point below the power line is towards?

1. A

   East

2. B

   West

3. C

   North

4. D

   South

Appeared in: KPSC Staff Nurse - 2016

Explanation

• The direction of the magnetic field produced by a current in a straight wire is determined by the Right-Hand Thumb Rule (also known as the Right-Hand Grip Rule).
• To apply the rule, you point the thumb of your right hand in the direction of the current (West to East).
• The direction that your fingers curl around the wire gives the direction of the circular magnetic field lines.
• When observing a point below the wire, the curled fingers point in the South direction.
• The magnetic field lines are always perpendicular to the direction of the current.

Why Other Options Were Wrong

• Option A: The magnetic field lines form circles around the wire and are perpendicular to the current's direction. The field cannot be in the same direction (East) as the current.
• Option B: The magnetic field is perpendicular to the current's direction. It cannot be in the opposite direction (West) of the current.
• Option C: This is the direction of the magnetic field at a point above the power line, not below it.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Direction of magnetic field around a current-carrying conductor as background academic context rather than a clinical decision trigger.
• This principle is fundamental to understanding electromagnetism, which is the basis for many technologies, including electric motors, generators, and transformers.
• Understanding the relationship between electricity and magnetism is crucial in physics and engineering for designing and troubleshooting electrical equipment.
• What if? - If the current flowed from East to West (the opposite direction), the magnetic field direction would also reverse. At a point below the wire, the field would then point North.

How to Approach the Question

• Identify the key information: The current direction is West to East, and the point of interest is below the wire.
• Recall the relevant physical law: The direction of the magnetic field around a straight current-carrying wire is determined by the Right-Hand Thumb Rule.
• Visualize the scenario: Picture the wire running horizontally from your left (West) to your right (East).
• Apply the rule: Point your right thumb to the right (East). Now, curl your fingers as if you are gripping the wire.
• Determine the direction at the specific point: Notice the direction your fingertips are pointing when they pass underneath the wire. They will be pointing towards you. In a standard geographical orientation where East is to your right, 'towards you' corresponds to South.
• Compare your result with the given options and select the correct one.

Concept Tested & Keywords

• Concept Tested: Direction of magnetic field around a current-carrying conductor
• Stem keywords: steady current, power line, west to east, magnetic field, below the power line
• Lead-in keywords: direction

Question ID

QDQHKpemYX_EIbeBha3Ile

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