The electric field due to a single positive point charge at distance r points in which direction?

The electric field due to a single positive point charge at distance r points in which direction?

• A. Toward the charge
• B. Tangential to a circle around the charge
• C. Perpendicular to the radius toward the charge
• D. Away from the charge

Answer: (D)

The electric field from a positive point charge radiates outward. At any point a distance r away, the field points along the line from the charge to that point, away from the charge. This follows from E = F/q: a small positive test charge placed in the field would experience a force in the same direction as the field, which for a positive source charge is away from the source. The magnitude is kq/r^2, but the direction remains outward along the radial line. So the field points away from the charge. Choices describing a direction toward the charge, tangential to a circle around the charge, or perpendicular to the radius toward the charge do not match the radial, outward nature of the field for a positive charge.

The electric field from a positive point charge radiates outward. At any point a distance r away, the field points along the line from the charge to that point, away from the charge. This follows from E = F/q: a small positive test charge placed in the field would experience a force in the same direction as the field, which for a positive source charge is away from the source. The magnitude is kq/r^2, but the direction remains outward along the radial line. So the field points away from the charge. Choices describing a direction toward the charge, tangential to a circle around the charge, or perpendicular to the radius toward the charge do not match the radial, outward nature of the field for a positive charge.