A conductor of length 0.5 m carries a current of 2 A and is pl... | General Science MCQ | Examoogle

General SciencePhysics: Magnetic Effects of Electric Current

A conductor of length 0.5 m carries a current of 2 A and is placed perpendicular to a magnetic field of 0.4 T. The force on the conductor is:

0.2 N

0.4 N

0.8 N

0.1 N

Correct Answer

🔬 SC • Science Concept & PrincipleGeneral SciencePhysics: Magnetic Effects of Electric Current

Option B

0.4 N

Quick Summary:

The force on a current-carrying conductor in a magnetic field is given by the Lorentz force law. For a straight conductor placed perpendicularly to a uniform magnetic field, the magnitude of the force is calculated by the product of current, length, and magnetic field intensity.

🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of this like a motor: the interaction between the electricity flowing through wires and the magnetic field creates a push that causes movement, similar to how a fan blade is pushed to spin.

🧠 Memory Mnemonic / Shortcut Aid

Remember 'BIL' (Force = $B \cdot I \cdot L$ )

🔢 Key Formulas

$F = B \cdot I \cdot L \cdot \sin(\theta)$ — The force on a current-carrying conductor

$F = B \cdot I \cdot L$ — Simplified form when the conductor is perpendicular to the magnetic field

⚙️ Working Principle

When a current $I$ flows through a conductor of length $L$ in a magnetic field $B$ , the magnetic force is given by $F = B \cdot I \cdot L \cdot \sin(\theta)$ . Since the conductor is placed perpendicular to the field, the angle $\theta = 90°$ and $\sin(90°) = 1$ . Substituting the values $B = 0.4 \text{ T}$ , $I = 2 \text{ A}$ , and $L = 0.5 \text{ m}$ , we get $F = 0.4 \times 2 \times 0.5 = 0.4 \text{ N}$ .

📌 Key Points

▸
The force is maximum when the conductor is perpendicular to the magnetic field.
▸
The force is zero when the current flows parallel or anti-parallel to the magnetic field.
▸
The direction of the force is determined by Fleming's Left-Hand Rule.

✅ Advantages

▸
Used in the construction of electric motors and loudspeakers.

❌ Disadvantages / Limitations

▸
The force magnitude decreases as the orientation of the wire approaches the parallel alignment with field lines.

🛠️ Applications / Uses

▸
Electric motors
▸
Galvanometers

📄 Additional Information

▸
Magnetic field strength ( $B$ ) is measured in Tesla (T).
▸
Option A ( $0.2 \text{ N}$ ) is calculated if the length or current is halved. Option C ( $0.8 \text{ N}$ ) is calculated if dimensions are miscalculated. Option D ( $0.1 \text{ N}$ ) is a common error from incorrect multiplication.

📊 Diagram / Illustration

✅

B is correct — The calculated magnetic force using $F = B \cdot I \cdot L$ results in $0.4 \text{ N}$ .

Core Concepts Used

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Lorentz Force Magnetic Field Effect Fleming's Left-Hand Rule

💡 EXAM TIP

Always check the angle between the conductor and the magnetic field; if not 90 degrees, remember to include the $\sin(\theta)$ term in your calculation.

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