Electric Fields
A test charge of 5.0 × 10⁻⁶ C is placed at a point in space and experiences an electric force of 1.5 × 10⁻² N directed north. What is the magnitude of the electric field at that location?
A negative charge is placed at a location where the electric field points to the left. What is the direction of the electric force on the charge?
Two charges, q₁ = +4.0 μC and q₂ = +4.0 μC, are placed on the x-axis at equal distances from the origin — q₁ to the left and q₂ to the right. What is the net electric field at the origin?
An engineer is designing a Faraday cage to shield sensitive electronic instruments from external electric fields. The cage is made of a hollow conducting shell. Which property of conductors in electrostatic equilibrium makes this shielding possible?
A solid conducting sphere of radius R carries total charge +Q. What is the electric field at a distance r = 4R from the center of the sphere?
Which statement correctly describes the difference between an electric field vector map and an electric field line diagram?
A student draws an electric field line diagram for two point charges and claims that two field lines cross at a point between the charges. What is wrong with this claim?
A solid conducting sphere of radius 0.10 m carries a charge of +2.0 × 10⁻⁶ C. Calculate the electric field magnitude at the surface of the sphere.
A solid insulating sphere and a solid conducting sphere have the same radius R and the same total charge +Q, both with spherically symmetric distributions. At a distance r = 3R from the center, how do their electric fields compare?
During a thunderstorm, the electric field near the tip of a tall metal lightning rod is much stronger than the field near the flat sides of the rod. Which principle of conductor electrostatics best explains why charge accumulates at the sharp tip and produces a stronger local field?
Two charges, q₁ = +3.0 μC at the origin and q₂ = −3.0 μC at x = 0.40 m, form a dipole. Calculate the net electric field at the midpoint between them.
The electric field at a certain point is measured to be 800 N/C directed downward. What force does a charge of −4.0 × 10⁻⁶ C experience at this point?
A student claims: “The electric field at a point exists only when a test charge is placed there to detect it.” Which response correctly addresses this claim?
A solid insulating sphere of radius R has charge +Q distributed uniformly throughout its volume. What is the electric field at the exact center of the sphere?
The charge on a conducting sphere is doubled from +Q to +2Q while the radius remains the same. By what factor does the electric field at a fixed point outside the sphere change?
A positive point charge +Q is at the origin. At point P, a distance d to the right, the electric field has magnitude E₀. A second positive charge +Q is now placed at a distance 3d to the right of the origin. What is the magnitude of the net electric field at point P?
A hollow conducting spherical shell has no charge placed inside its cavity. A student claims the electric field is zero inside the cavity solely because no charges are present there. Is this reasoning complete?
An insulating rod is given a net positive charge by rubbing. The charge remains on the section of the rod that was rubbed rather than spreading uniformly over the entire surface. Which property of insulators explains this observation?