Question 71 of 949
A conductor of length 2m carries a current of 0.8A while kept in a magnetic field of magnetic flux density 0.5T. The maximum force acting on it is
- A. 0.2N
- B. 0.8N
- C. 3.2N
- D. 8.0N
Correct Answer:
B
Explanation
To determine the maximum force acting on a conductor carrying a current in a magnetic field, we can use the formula:
\[ F = BIL \sin(\theta) \]
Where:
- \( F \) is the force in newtons (N),
- \( B \) is the magnetic flux density in teslas (T),
- \( I \) is the current in amperes (A),
- \( L \) is the length of the conductor in meters (m),
- \( \theta \) is the angle between the direction of the magnetic field and the direction of the current.
### Step-by-Step Explanation
1. **Identify the Given Values**:
- Length of the conductor, \( L = 2 \, \text{m} \)
- Current, \( I = 0.8 \, \text{A} \)
- Magnetic flux density, \( B = 0.5 \, \text{T} \)
2. **Determine the Angle**:
- The maximum force occurs when the angle \( \theta \) is 90 degrees (i.e., when the conductor is perpendicular to the magnetic field). At this angle, \( \sin(90^\circ) = 1 \).
3. **Substitute the Values into the Formula**:
- Since we are looking for the maximum force, we can set \( \sin(\theta) = 1 \):
\[
F = BIL \sin(90^\circ) = BIL
\]
\[
F = (0.5 \, \text{T}) \times (0.8 \, \text{A}) \times (2 \, \text{m})
\]
4. **Calculate the Force**:
\[
F = 0.5 \times 0.8 \times 2
\]
\[
F = 0.5 \times 1.6 = 0.8 \, \text{N}
\]
### Conclusion
The maximum force acting on the conductor is **0.8 N**. Therefore, the correct option is **B**.
### Explanation of Other Options
- **Option A: 0.2 N**: This value is too low. It may arise from a misunderstanding of the formula or incorrect substitution of values.
- **Option C: 3.2 N**: This value could be mistakenly calculated by incorrectly multiplying the values or assuming a different angle.
- **Option D: 8.0 N**: This value is significantly higher than expected and likely results from a miscalculation or misunderstanding of the relationship between the variables.
### Common Pitfalls
- **Forgetting the Angle**: Always remember that the angle affects the force calculation. The maximum force occurs at 90 degrees.
- **Incorrect Units**: Ensure that all units are consistent (e.g., meters for length, amperes for current, teslas for magnetic flux density).
- **Misapplication of the Formula**: Make sure to use the correct formula and understand each component's role in the calculation.
### Revision Summary
- The force on a conductor in a magnetic field is given by \( F = BIL \sin(\theta) \).
- Maximum force occurs at \( \theta = 90^\circ \) where \( \sin(90^\circ) = 1 \).
- For the given values, the maximum force is calculated as \( 0.8 \, \text{N} \).
- Always check units and ensure correct application of the formula to avoid common mistakes.