AP Physics 2 Unit 2 Progress Check C

The figure represents the vertical electric field near the center of two long, horizontal parallel plates near Earth's surface. The electric field has magnitude 2200N/C2200N/C, and the plates are separated by 0.08m0.08m. A small object with a mass of 2.2×10−8kg2.2×10−8kg and a charge of −7.2×10−11C−7.2×10−11C is released at a point midway between the plates.

0.6×10−7 N

The figure represents the vertical electric field near the center of two long, horizontal parallel plates near Earth's surface. The electric field has magnitude 2200N/C2200N/C, and the plates are separated by 0.08m0.08m. A small object with a mass of 2.2×10−8kg2.2×10−8kg and a charge of −7.2×10−11C−7.2×10−11C is released at a point midway between the plates.

176V

Point charges Q1Q1, Q2Q2, and Q3Q3 produce an electric field with a magnitude of 100N/C100N/C directed to the right at point PP, as shown in the figure. If the sign of each of the three charges is reversed and the magnitude of each charge is doubled, what is the resulting electric field at point PP ?

200N/C200N/C directed to the left

Sphere AA with charge +2nC+2nC is placed with its center 1.5cm1.5cm from the center of sphere BB with charge −4nC−4nC, as shown in the figure. What is the magnitude of the electric force on charge AA due to charge BB?

3.2×10−4N

Sphere AA with charge +2nC+2nC is placed with its center 1.5cm1.5cm from the center of sphere BB with charge −4nC−4nC, as shown in the figure. Which of the following diagrams best represents the electric forces acting on spheres AA and BB, with the correct directions and relative magnitudes?

A and B Are both pointing towards each other with the same distance

The strength of the electric field surrounding a charged metal sphere is inversely proportional to the square of the distance rr from the center of the sphere. Which of the following best explains this phenomenon?

As the distance increases, the field must pass through spherical surfaces that are increasingly larger in area, and the area of a sphere is proportional to the radius squared.

The diagrams show field vectors for a single object AA and for object AA placed next to identical object BB . Which of the following properties of objects AA and BB could describe the field vectors shown? Select two answers.

Both are negatively charged. Both are massive.

Sphere AA with charge +2nC+2nC is placed with its center 1.5cm1.5cm from the center of sphere BB with charge −4nC−4nC, as shown in the figure. How would the magnitude of the electric force exerted on sphere AA change, if at all, if the charge on sphere BB was doubled and the distance of separation remained the same?

It would double.

The centers of two identical spheres of charge QQ and mass MM are separated by a distance rr . The only forces acting on each sphere are the gravitational and electrical forces exerted by the other sphere. The net force on each sphere is zero. Which of the following correctly relates MM and QQ ?

M=14πε0G−−−−−√Q

Two spheres with charges −q−q and +3q+3q are separated by a distance DD, as shown in the figure. They exert a force of magnitude FF on each other. Which of the following changes will result in the spheres exerting a force of magnitude 2F2F on each other?

Making the charge on the left sphere −2q

Four particles are arranged at the corners of a square, as shown in the diagram. Two particles have charge +Q1+Q1, one particle has charge −Q2−Q2, and one particle has charge +q+q. The net force exerted on the particle of charge +q+q by the other three particles is zero. What is the magnitude of Q2Q2 in terms of Q1Q1?

Q2=22√Q1

The electric field at a distance RR from an isolated particle with charge QQ has a magnitude of 3200 N3200 N. At what distance from the particle is the magnitude of the electric field 6400 N6400 N?

R/2√

Which of the following correctly indicates a similarity and a difference when Coulomb's law for electrostatic force and Newton's law of gravitation are compared?

Similarity Doubling the magnitude of one charge or one mass doubles the force between two objects. Difference The electrostatic force can be attractive or repulsive, but the gravitational force is only attractive.

An electron is accelerated in an electric field through a potential difference of +2400V+2400V. Which of the following justifies why the change in kinetic energy can be calculated using ΔU=qΔVΔU=qΔV?

The change in potential energy of the field-electron system is equal to the change in kinetic energy of the particle.

A small planet is discovered to have a layer of electrically charged dust floating at 1000m1000m above the surface because of the balance between the gravitational forces and electrical forces exerted on the dust by the planet. If the dust layer is moved to 2000m2000m above the surface, what will happen to the dust, and why?

The dust will continue to float because the gravitational force will still balance the electrical force.

Which of the following best explains why the electric field of a charged particle is inversely proportional to the square of the distance from the particle?

The field spreads out over a sphere centered on the particle. So the magnitude will decrease in proportion to the surface area of the sphere, 4πr2.

Consider three systems: an isolated point mass, an isolated electron, and an electric dipole consisting of a proton and an electron. Which of the following correctly describes the field associated with each system?

The field surrounding the isolated mass and that surrounding the isolated electron point toward the point mass and electron, respectively, while the field surrounding the dipole trends away from the proton and toward the electron.

Two identical blocks each have a mass of 1.00kg1.00kg and a net charge of +1.00μC+1.00μC each. Which of the following statements is true regarding the relative magnitudes of the electric and gravitational force each block exerts on the other?

The magnitude of the electric force is much larger than the magnitude of the gravitational force.

Which of the following best shows the electric potential isolines around a charged sphere and the gravitational potential isolines around a small moon? (Objects are not to scale.)

Two circles withs circles rings with dotted lines around them

A negatively charged plastic sphere is given a charge of −4.0μC−4.0μC and launched perpendicularly into a region with a 500N/C500N/C electric field directed to the right, as shown in the figure. Assuming gravitational effects are negligible, which of the following could represent the direction of the acceleration of the plastic sphere at a point within the field?

arrow horizontal to the left