Exam 20: Electric Fields and Forces

Two infinite parallel plastic sheets contain equal negative charge densities uniformly spread over their surfaces.The electric field is zero everywhere between these sheets,not just midway between them.

If two point charges exert a force of 1 N on each other when they are 3 cm apart,they will exert a force of 1/25 N when they are 15 cm apart.

The electrical force between two objects depends on

-A pair of charged conducting plates produces a uniform field of 12,000 N/C,directed to the right,between the plates.The separation of the plates is 40 mm.In the figure,an electron is projected from plate A,directly toward plate B,with an initial velocity of vo = 2.0 × 10⁷ m/s.The velocity of the electron as it strikes plate B is closest to:

An asteroid of mass 58,000 kg carrying a negative charge of 15.0 μC is 180 m from a second asteroid of mass 52,000 kg carrying a negative charge of 11.0 μC .What is the net force the asteroids exert upon each other? (G = 6.673 × 10^-11 N·m²/kg² and k = 9.0 × 10⁹ N·m²/C². )

Four charged particles (two having a charge +Q and two having a charge -Q)are distributed as shown below.Each charge is equidistant from the origin.In which direction is the net electric field at the point P,which is on the y axis?

A positive charge moving along the x-axis passes a negative charge of equal magnitude moving at the same speed but in the opposite direction.The negative charge is only slightly displaced from the x-axis.A point charge is stationary near,but not on,the x-axis,and has the same x-coordinate as the moving charges at the point where they will be closest to each other.Will the point charge experience an electric field that is greater than or less than the field that would result if there were only one moving charge?

The diagram shows two unequal charges +q and -Q,of opposite sign.Charge Q has greater magnitude than charge q.Point X is midway between the charges. In what section of the line will there be a point where the resultant electric field is zero?

X and Y are two uncharged metal spheres on insulating stands,and are in contact with each other.A positively charged rod R is brought close to X as shown in figure 1. Sphere Y is now moved away from X (figure 2). The final charge states of X and Y,respectively,are

An object with a 5.0 μC charge is accelerating at 0.0050 m/s²due to an electric field.If the object has a mass of 2.0 mg,what is the magnitude of the electric field?

If one bag contains a charge 8Q and another one contains charge Q,the 8Q-bag exerts 8 times as much force on the Q-bag as the Q-bag exerts on the 8Q-bag.

Two neutral objects cannot attract each other electrically because they have no excess charge.

What is the electric field strength at x = 0 m,y = 0 m produced by two electrons,one at x = 0.0001 m,y = 0 m and the other at x = -0.0001 m,y = 0 m? (The value of k is 9.0 × 10⁹ N·m²/C². )

Electric field lines begin on negative charges and end on positive charges.

Two nuclei each contain two protons and exert a force 4 N on each other.If we transfer a proton from one of these nuclei to the other,the force on each nucleus is now reduced to 3 N.

In the figure below the charge in the middle is Q = -3.1 nC.For what charge q1 will charge q2 be in static equilibrium?

Two unequal point charges q1 and q2 are held in place separated from each other.A point charge Q is placed somewhere between them at a point where it remains stationary when released.From this observation,we can conclude that q1 and q2 must either both be positive or both be negative.

The electric field at point P due to a point charge Q a distance R away has magnitude E.In order to double the magnitude of the field at P,you could

When electric field lines are curved,the electric field at any point is tangent to the field line at that point.

A proton is located at x = 1.0 nm,y = 0.0 nm and an electron is located at x = 0.0 nm, y = 4.0 nm.Find the attractive Coulombic force between them.(The value of k is 9.0 × 10⁹ N·m²/C². )