Understanding the Concepts
* Electric Field: An electric field is a region around a charged object where a force would be exerted on another charged object.
* Electric Field Strength (E): The electric field strength at a point is the force per unit charge that would be experienced by a test charge placed at that point.
* Coulomb's Law: This law describes the force between two point charges. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
Formula
The magnitude of the electric field strength (E) at a distance (r) from a point charge (q) is given by:
E = k * |q| / r²
where:
* E is the electric field strength (N/C)
* k is Coulomb's constant (approximately 8.98755 × 10⁹ N·m²/C²)
* |q| is the magnitude of the point charge (C)
* r is the distance from the point charge (m)
Calculations
1. Identify the values:
* q = 4.2 × 10⁻⁹ C
* r = 1.2 m
2. Plug the values into the formula:
* E = (8.98755 × 10⁹ N·m²/C²) * (4.2 × 10⁻⁹ C) / (1.2 m)²
3. Calculate the result:
* E ≈ 26.26 N/C
Answer
The magnitude of the electric field strength at a position 1.2 m from a point charge of 4.2 × 10⁻⁹ C is approximately 26.26 N/C.
