The force per unit charge experienced at a point in a field is the

Step 1: Analyze the question The question asks which quantity is defined as "force per unit charge" at a point in a field. The key phrase is per unit charge.

Step 2: Explain the concept Fields are defined by the force they exert on a test "unit" of something:

• Gravitational field strength is force per unit mass: g = F/m (unit: N/kg)
• Electric field intensity is force per unit charge: E = F/q (unit: N/C)
• Electric potential is work done per unit charge: V = W/q (unit: J/C or volts). It involves energy, not force.
• Magnetic field strength (flux density) is force per unit charge per unit velocity, or force per unit current-length: B = F/(qv) or B = F/(IL). It is not simply force per unit charge.

Step 3: Solve Using the definition:

E = F / q

This is the force experienced by a unit positive charge placed at a point in an electric field. It matches the question exactly.

Checking the options:

• A: force per unit mass, so wrong
• B: work (energy) per unit charge, so wrong
• C: force per unit charge, so correct
• D: involves velocity or current length as well, so wrong

Step 4: Answer The correct option is C. electric field intensity.

Exam tip: Match the "per unit" word to the field:

• per unit mass → gravitational field
• per unit charge → electric field
• per unit charge but energy/work → electric potential

Remember that force gives field, while work or energy gives potential.