Field Strength

Definition

Field strength is a measure of the magnitude or intensity of a physical field, such as an electric field or a magnetic field, at a particular location. It quantifies the force exerted per unit charge or per unit mass within the field.

5 Must Know Facts For Your Next Test

1. Field strength is often denoted by the symbol $E$ for electric fields and $B$ for magnetic fields, and is measured in units of newtons per coulomb (N/C) or teslas (T).
2. The field strength at a particular point in space is determined by the magnitude and direction of the force exerted on a test charge or object placed at that point.
3. Electric field lines are used to visualize the direction and strength of an electric field, with the density of the lines indicating the field strength.
4. The field strength of an electric field decreases with the square of the distance from the source charge, in accordance with Coulomb's law.
5. Magnetic field strength is related to the number of magnetic field lines passing through a unit area perpendicular to the field direction.

Review Questions

• Explain how the field strength of an electric field is related to the force exerted on a test charge.
  • The field strength of an electric field is directly proportional to the force exerted on a test charge placed within the field. Specifically, the electric field strength $E$ at a given point is equal to the force $F$ acting on a test charge $q$ at that point, divided by the magnitude of the test charge: $E = F/q$. This relationship allows us to quantify the intensity of an electric field by measuring the force experienced by a known test charge.
• Describe how the field strength of an electric field varies with distance from the source charge.
  • The field strength of an electric field decreases with the square of the distance from the source charge, in accordance with Coulomb's law. This inverse-square relationship means that as the distance from the source charge doubles, the field strength decreases by a factor of four. This pattern is visually represented by the decreasing density of electric field lines as you move farther away from the charge. Understanding this distance-dependent behavior of field strength is crucial for analyzing and predicting the effects of electric fields.
• Analyze how the field strength of a magnetic field is related to the number of magnetic field lines passing through a unit area.
  • The field strength of a magnetic field, denoted as $B$, is directly proportional to the number of magnetic field lines passing through a unit area perpendicular to the field direction. The more densely packed the magnetic field lines are in a given region, the stronger the magnetic field strength at that location. This relationship allows us to visualize and quantify the intensity of a magnetic field by examining the distribution and concentration of its field lines. Understanding this connection between field line density and field strength is essential for interpreting and applying magnetic field concepts.

Related terms

Electric Field: An electric field is a region of space surrounding an electric charge where other electric charges experience a force.

Magnetic Field:

A magnetic field is a region of space surrounding a magnet or a moving electric charge where magnetic forces can be detected.

Force:

A force is a vector quantity that can cause an object to change its velocity, shape, or direction of motion.