Field Due to Current-Carrying Conductor MCQs Quiz | Class 10

Welcome to this Class X Science (Code 086) quiz from Unit IV: Effects of Current. This quiz focuses on ‘Field Due to Current-Carrying Conductor’, covering essential concepts like magnetic fields produced by a straight conductor and the fundamental direction rule (Right-Hand Thumb Rule). Test your knowledge with 10 multiple-choice questions. After submission, you can review your answers and download a detailed PDF of your performance.

Understanding Magnetic Fields Due to Current-Carrying Conductors

The study of magnetic effects of electric current is a cornerstone of electromagnetism. When electric current flows through a conductor, it generates a magnetic field around it. The pattern and direction of this magnetic field depend on the shape of the conductor and the direction of current flow.

Magnetic Field Due to a Straight Current-Carrying Conductor

A straight wire carrying electric current produces a magnetic field in the form of concentric circles around it. These magnetic field lines lie in a plane perpendicular to the wire. The center of these concentric circles is the conductor itself. The density of these field lines indicates the strength of the magnetic field; lines are denser closer to the wire and become farther apart as the distance from the wire increases, signifying a weaker field further away.

Direction of Magnetic Field: The Right-Hand Thumb Rule

To determine the direction of the magnetic field lines around a straight current-carrying conductor, we use the Right-Hand Thumb Rule (also known as Maxwell’s Corkscrew Rule). This rule states:

Imagine you are holding the current-carrying straight conductor in your right hand such that your thumb points in the direction of the current. Then, the direction in which your fingers curl around the conductor gives the direction of the magnetic field lines.

For example, if the current flows upwards, and you point your right thumb upwards, your fingers will curl in an anti-clockwise direction when viewed from above. If the current flows downwards, the field lines will be clockwise when viewed from above.

Factors Affecting the Strength of the Magnetic Field

The strength of the magnetic field produced by a straight current-carrying conductor depends on two main factors:

  1. Magnitude of Current: The magnetic field strength is directly proportional to the magnitude of the current flowing through the conductor. This means that if you increase the current, the magnetic field produced will also become stronger.
  2. Distance from the Conductor: The magnetic field strength is inversely proportional to the distance from the conductor. As you move farther away from the wire, the magnetic field becomes weaker. Conversely, closer to the wire, the magnetic field is stronger.

Key Characteristics of Magnetic Field Lines

  • They form concentric circles centered on the wire.
  • They lie in a plane perpendicular to the conductor.
  • Their direction is given by the Right-Hand Thumb Rule.
  • The field is stronger where the lines are closer (near the wire) and weaker where they are farther apart (away from the wire).

Quick Revision

  • Current creates a magnetic field.
  • Straight wire: concentric circular field lines.
  • Right-Hand Thumb Rule determines field direction.
  • Field strength increases with current.
  • Field strength decreases with distance.

Practice Questions

  1. Describe the pattern of magnetic field lines around a straight current-carrying conductor.
  2. State and explain the Right-Hand Thumb Rule for finding the direction of the magnetic field.
  3. How does the magnetic field strength vary with the magnitude of current and the distance from the conductor?
  4. A compass needle is placed near a straight wire carrying current. What will happen to the needle? How would its deflection change if the current direction is reversed?
  5. What would be the direction of magnetic field lines at a point directly above a horizontal wire carrying current from west to east?