PHY102

Two very small plastic balls of equal mass are released from rest. One of them carries +10 μC of excess charge and the other one carries +1μC of charge. No other charges or fields are present. Which of the following statements are true about them as they move away from each other?

1. Have accelerations of equal magnitude. 2. speed of the balls keeps increasing

How much work must we do on an electron to move it from point A, which is at a potential of +50V, to point B, which is at a potential of -50 V, along the semicircular path shown in the figure? Assume the system is isolated from outside forces.

1.60 × 10-17 J

Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F due to the other. With time, charge gradually diminishes on both spheres by leaking off. When each of the spheres has lost half its initial charge, what will be the magnitude of the electrostatic force on each one?

1/4F

Two charges, Q1 and Q2, are separated by a certain distance. The ratio of charge Q1 to charge Q2 is 1:2. The ratio of force on Q1 to the force on Q2 is

1:1

Two charged dust particles exert a force of 6.0×10−2 NN on each other. What will be the force if they are moved so they are only 1/8th as far apart?

3.8 N

Two point charges of +30.0 µC and -9.00 µC are separated by a distance of 20.0 cm. What is the intensity of electric field E midway between these two charges?

35.1 × 106 N/C directed towards the negative charge

Two point charges of +30.0 µC and -9.00 µC are separated by a distance of 20.0 cm. What is the intensity of electric field E midway between these two charges?

35.1 × 10^6 N/C directed towards the negative charge

If the voltage across a circuit of constant resistance is doubled, the power dissipated by that circuit will

4 times as large

A person scuffing her feet on a wool rug on a dry day accumulates a net charge of -95 μCμC . How many excess electrons does she get? By how much does her mass increase?

5.9x10^14 electrons Δm =5.4×10^−16 kg

At a certain point in space the electric potential is 20 V. A 4.0 μC charge is brought in from infinity to that point. What is the electric potential energy of this charge at that point?

80 μJ

Two charges, Q1 and Q2, are separated by a certain distance R. If the magnitude of their charges is halved, and their separation is doubled, then what happens to the electrical forces between these charges?

Decreases by factor of 16

Two charges, Q1 and Q2, are separated by a certain distance R. If the magnitudes of their charges are doubled and their separation is halved, then what happens to the electrical force between these charges?

It increases by a factor of 16.

The magnitude of a force between two equal charges is 4 N when the separation is 2 m. If the charge separation becomes 6 m, then what happens to the magnitude of the force between them?

It is 4/9 N

Four equal charges are located at the corners of a square of side d. If the magnitude of each charge is doubled and the length of each side of the square is also doubled then what happens to the resultant force on each charge?

It remains the same

Two point charges, Q1 and Q2, are separated by a distance R. If the magnitudes of both charges are halved and their separation is also halved, what happens to the electrical force that each charge exerts on the other one?

It remains the same.

Two charges, Q1 and Q2, are separated by a certain distance R. If the magnitudes of the charges are doubled and their separation is also doubled, then what happens to the electrical force between these two charges?

Remains the Same

Two point charges, Q1 and Q2, are separated by a distance R. If the magnitudes of both charges are doubled and their separation is also doubled, what happens to the electrical force that each charge exerts on the other one?

Remains the same

Two tiny beads are 25 cm apart with no other charges or fields present. Bead A carries 10 µC of charge and bead B carries 1 µC. Which one of the following statements is true about the magnitudes of the electric forces on these beads?

The force on A is exactly equal to the force on B.

A charged rod carrying a negative charge is brought near two spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?

The sphere near the charged rod becomes positive and the other becomes negative.

A negatively-charged rod is brought close to (but does not touch) two neutral spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?

The sphere near the charged rod becomes positive and the other one becomes negative.

An electron and a proton are released simultaneously from rest and start moving toward each other due to their electrostatic attraction, with no other forces present. Which of the following statements are true just before they are about to collide? (There could be more than one correct choice.)

They are closer to the to the initial position of the proton that to the initial position of the electron.

Doubling the capacitance of a capacitor that is holding a constant charge causes the energy stored in that capacitor to

decrease to one-half

a positive charge, if free to move, tries to move

from high potential to low potential

A plastic rod is charged up by rubbing a wool cloth, and brought to an initially neutral metallic sphere that is insulated from ground. It is allowed to touch the sphere for a few seconds, and then is separated from the sphere by a small distance. After the rod is separated, the rod

is repelled by the sphere

A glass marble is rubbed against a piece of silk. As a result the piece of fabric acquires extra electrons. What happens to the glass marble?

lost the same number of electrons acquired by the silk marble acquires a positive charge and attracts the piece of silk

Two glass marbles (1 and 2), each supported by a nylon thread, are rubbed against a piece of silk and then are placed near a third glass marble (3), also supported by a similar thread. Assuming that marble 3 has not been in contact with the piece of fabric, which of the following statements best describes the situation when the three marbles are brought together?

marbles 1 and 2 repel but there is no other interaction with marble 3

A small metal ball hangs from the ceiling by an insulating thread. The ball is attracted to a positively charged rod held near the ball.

negative or neutral

A negatively-charged plastic rod is brought close to (but does not touch) a neutral metal sphere that is connected to ground. After waiting a few seconds, the ground connection is removed (without touching the sphere), and after that the rod is also removed. The sphere is now

positively charged

A negatively-charged plastic rod is brought close to (but does not touch) a neutral metal sphere that is connected to ground. After waiting a few seconds, the ground connection is removed (without touching the sphere), and after that the rod is also removed. The sphere is now (

positively charged

When the magnitude of two charges is increased by a factor of 2, the electrical forces between these charges is

quadrupled

When the distance between the two charges is doubled, the force between them is

reduced by a factor of 4

Two uncharged metal spheres, #1 and #2, are mounted on insulating support rods. A third metal sphere, carrying a positive charge, is then placed near #2. Now a copper wire is momentarily connected between #1 and #2 and then removed. Finally, sphere #3 is removed. In this final state

sphere #1 carries positive charge and #2 carries negative charge.

The charge on the proton is the same as

the charge on the electron, but of the opposite sign