Question 1

About how many electrons are in 0.3 gram of water (H₂O)?

Accepted Answer

A

Question 2

Object A has a charge q on it, object B has a charge q on it, and object C has a charge 2q on it. These charges are arranged, one each, at the vertices of an equilateral triangle. Which charge has the greatest magnitude electric force on it?

Accepted Answer

Using Coulomb's law, the force on a charge is proportional to the product of the two charges and inversely proportional to the square of the distance between them. The distances between each pair of charges are equal, so we only need to consider the magnitudes of the charges.

The force on A is generated by q and 2q, so it is the sum of the forces from these two charges. The force on B is generated by q and 2q, but because B is equidistant from both charges, the forces cancel each other out. Therefore, the only charge that experiences a net force is C, and the force on C is generated by the charges on A and B. Thus, the magnitude of the force on C is

F = k(q)(2q)/(a^2)

where k is Coulomb's constant and a is the length of a side of the triangle. The magnitude of the force on A is

F = k(q)(2q)/(a^2) + k(q)(q)/(a^2)

so we can see that the force on C is greater than the force on A. Therefore, the correct answer is B.

Question 3

Two identical iron spheres have equal positive charges and the force between them when they are 1 m apart is 4 N. What percentage of the electrons has been removed from each sphere if each sphere has 1 mole (6 *10²³) of iron atoms? (k_e = 8.99 * 10⁹N.m²/C², the atomic number of iron is 26, and the electron charge is -1.6 *10 ^- ¹⁹ C)

Accepted Answer

A

Question 4

Two point charges, separated by 15 cm, have charge values of +2.0 µC and -4.0 µC, respectively. What is the value of the mutual force between them? (k_e = 8.99 * 10⁹ N.m²/C²)

Accepted Answer

The mutual force between two point charges is calculated using Coulomb's law: F = k_e * |q1 * q2| / r^2. Substituting the given values: F = (8.99 x 10^9 N·m²/C²) * |2.0 x 10^-6 C * -4.0 x 10^-6 C| / (0.15 m)² = 3.2 N.

Question 5

The constant k_e, which appears in Coulomb's law formula, is equivalent dimensionally to which of the following?

Accepted Answer

Coulomb's constant k_e has the dimensions of N·m²/C², which matches option B.

Question 6

Two identical balls have the same amount of charge, but the charge on ball A is positive and the charge on ball B is negative. The balls are placed on a smooth, level, frictionless table whose top is an insulator. Which of the following is true?

Accepted Answer

The answer of Two identical balls have the same amount...

Question 7

If the size of the charge value is tripled for one of two point charges maintained at a constant separation, the mutual force between them will be changed by what factor?

Accepted Answer

The answer of If the size of the charge value...

Question 8

If the distance between two point charges is quadrupled, the mutual force between them will be changed by what factor?

Accepted Answer

The answer of If the distance between two point charges...

Question 9

Two identical spheres each carry a charge of -40.0 µC. The spheres are separated by a distance of 2.00 m. What is the electric force between the spheres? (k_e = 8.99*10⁹ N·m²/C²)

Accepted Answer

The electric force between two charges is calculated using Coulomb's law: F = k_e * |q1 * q2| / r^2. Substituting the given values: F = (8.99 x 10^9 N·m²/C²) * (40.0 x 10^-6 C)^2 / (2.00 m)^2 = 3.60 N. Since both charges are positive, the force is repulsive.

Question 10

A repelling force must occur between two charged objects under which conditions?

Accepted Answer

A repelling force occurs between two charged objects when they have like signs, meaning both are either positive or both are negative.

Question 11

Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge. What happens?

Accepted Answer

When Doug rubs the fur on the rubber rod, electrons are transferred from the fur to the rod, giving the rod a negative charge.

Question 12

Two electrons are separated by one cm. What is the ratio of the electric force to the gravitational force between them? (m_e = 9.11*10 ^- ³¹kg, k_e = 8.99 * 10⁹ N.m²/C², G = 6.67 * 10^-11 N.m²/kg², and e = 1.6 *10 ^- ¹⁹ C)

Accepted Answer

The answer of Two electrons are separated by one cm....

Question 13

The charge per unit length on an insulator is  . On a 2.0-m length of this material, what is the difference in the number of electrons and the number of protons?

Accepted Answer

The answer of The charge per unit length on an...

Question 14

Two point charges are 4 cm apart. They are moved to a new separation of 8 cm. By what factor does the resulting mutual force between them change?

Accepted Answer

The answer of Two point charges are 4 cm apart....

Question 15

A 6.00-$\mu$C charge is placed at the origin and a second charge is placed on the x axis at x = 0.300 m. If the resulting force on the second charge is 6.40 N in the negative x direction, what is the force on the charge at the origin?

Accepted Answer

According to Newton's third law, the force on the charge at the origin will be equal in magnitude and opposite in direction to the force on the second charge. Therefore, it is 6.40 N in the positive x direction.

Question 16

A 6.0-mC charge is placed at the origin and a second charge is placed on the x axis at x = 0.30 m. If the resulting force on the second charge is 5.4 N in the positive x direction, what is the value of its charge?

Accepted Answer

The force between two charges is given by Coulomb's law: F = k * |q1 * q2| / r^2. Given F = 5.4 N, q1 = 6.0 mC = 6.0 x 10^-3 C, r = 0.30 m, and k = 8.99 x 10^9 N m^2/C^2, solving for q2 gives q2 = 9.0 x 10^-9 C = 9.0 nC.

Question 17

An electron is sent at high speed toward a gold nucleus (charge +79e). What is the electrical force acting on the electron when it is 3.0*10 ^- ¹³ m away from the gold nucleus? (e = 1.6 *10 ^- ¹⁹ C, k_e = 8.99 * 10⁹ N·m²/C²)

Accepted Answer

The answer of An electron is sent at high speed...

Question 18

A metallic object holds a charge of -2.9 *10^-⁵C. What total number of electrons does this represent? (e = 1.6 *10^-¹⁹ C is the magnitude of the electronic charge.)

Accepted Answer

The charge on an electron is -1.6 x 10^-19 C. So, the number of electrons is:F1F1F1S1F1F1F102.9 F1F1F1S1F1F1F10 10F1F1F1S1^F1F1F10⁵C / (-1.6 x 10^-19 C) = 1.8 x 10^14 electrons

Question 19

Two equal charges, each Q, are separated by some distance. What third charge would need to be placed half way between the two charges so that the net force on each charge would be zero?

Accepted Answer

To make the net force on each charge zero, the third charge must exert an equal and opposite force to the force between the two charges. By placing a charge of -Q/4 halfway, it balances the forces due to the symmetry and equal magnitude of the charges.

Question 20

In a thundercloud there may be an electric charge of +40 C near the top of the cloud and -40 C near the bottom of the cloud. These charges are separated by about 2.0 km. What is the electric force between these two sets of charges? (k_e = 8.99 * 10⁹ N·m²/C²)

Accepted Answer

The electric force between two charges is given by Coulomb's law:$$F = k\frac{q_1q_2}{d^2}$$where:* k is Coulomb's constant (8.99 x 10^9 N·m^2/C^2)* q_1 and q_2 are the charges of the two objects (in Coulombs)* d is the distance between the two objects (in meters)In this problem, we have:* q_1 = +40 C* q_2 = -40 C* d = 2.0 km = 2000 mPlugging these values into Coulomb's law, we get:$$F = (8.99 x 10^9 N·m^2/C^2)\frac{(+40 C)(-40 C)}{(2000 m)^2}$$$$F = 3.6 x 10^6 N$$Therefore, the electric force between the two sets of charges is 3.6 x 10^6 N.

Quiz 17: Electric Forces and Fields

About how many electrons are in 0.3 gram of water (H₂O) ?

Object A has a charge q on it, object B has a charge q on it, and object C has a charge 2q on it. These charges are arranged, one each, at the vertices of an equilateral triangle. Which charge has the greatest magnitude electric force on it?

Two point charges, separated by 15 cm, have charge values of +2.0 µC and -4.0 µC, respectively. What is the value of the mutual force between them? (k_e = 8.99 * 10⁹ N.m²/C²)

The constant k_e, which appears in Coulomb's law formula, is equivalent dimensionally to which of the following?

Two identical balls have the same amount of charge, but the charge on ball A is positive and the charge on ball B is negative. The balls are placed on a smooth, level, frictionless table whose top is an insulator. Which of the following is true?

If the size of the charge value is tripled for one of two point charges maintained at a constant separation, the mutual force between them will be changed by what factor?

If the distance between two point charges is quadrupled, the mutual force between them will be changed by what factor?

Two identical spheres each carry a charge of -40.0 µC. The spheres are separated by a distance of 2.00 m. What is the electric force between the spheres? (k_e = 8.99*10⁹ N·m²/C²)

A repelling force must occur between two charged objects under which conditions?

Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge. What happens?

Two electrons are separated by one cm. What is the ratio of the electric force to the gravitational force between them? (m_e = 9.1110 ^- ³¹kg, k_e = 8.99 10⁹ N.m²/C², G = 6.67 * 10^-11 N.m²/kg², and e = 1.6 *10 ^- ¹⁹ C)

The charge per unit length on an insulator is . On a 2.0-m length of this material, what is the difference in the number of electrons and the number of protons?

Two point charges are 4 cm apart. They are moved to a new separation of 8 cm. By what factor does the resulting mutual force between them change?

A 6.00- $\mu$ C charge is placed at the origin and a second charge is placed on the x axis at x = 0.300 m. If the resulting force on the second charge is 6.40 N in the negative x direction, what is the force on the charge at the origin?

A 6.0-mC charge is placed at the origin and a second charge is placed on the x axis at x = 0.30 m. If the resulting force on the second charge is 5.4 N in the positive x direction, what is the value of its charge?

An electron is sent at high speed toward a gold nucleus (charge +79e) . What is the electrical force acting on the electron when it is 3.010 ^- ¹³ m away from the gold nucleus? (e = 1.6 10 ^- ¹⁹ C, k_e = 8.99 * 10⁹ N·m²/C²)

A metallic object holds a charge of -2.9 10^-⁵C. What total number of electrons does this represent? (e = 1.6 10^-¹⁹ C is the magnitude of the electronic charge.)

Two equal charges, each Q, are separated by some distance. What third charge would need to be placed half way between the two charges so that the net force on each charge would be zero?

In a thundercloud there may be an electric charge of +40 C near the top of the cloud and -40 C near the bottom of the cloud. These charges are separated by about 2.0 km. What is the electric force between these two sets of charges? (k_e = 8.99 * 10⁹ N·m²/C²)

Quiz 17: Electric Forces and Fields

About how many electrons are in 0.3 gram of water (H2O) ?

Object A has a charge q on it, object B has a charge q on it, and object C has a charge 2q on it. These charges are arranged, one each, at the vertices of an equilateral triangle. Which charge has the greatest magnitude electric force on it?

Two point charges, separated by 15 cm, have charge values of +2.0 µC and -4.0 µC, respectively. What is the value of the mutual force between them? (ke = 8.99 * 109 N.m2/C2)

The constant ke, which appears in Coulomb's law formula, is equivalent dimensionally to which of the following?

Two identical balls have the same amount of charge, but the charge on ball A is positive and the charge on ball B is negative. The balls are placed on a smooth, level, frictionless table whose top is an insulator. Which of the following is true?

If the size of the charge value is tripled for one of two point charges maintained at a constant separation, the mutual force between them will be changed by what factor?

If the distance between two point charges is quadrupled, the mutual force between them will be changed by what factor?

Two identical spheres each carry a charge of -40.0 µC. The spheres are separated by a distance of 2.00 m. What is the electric force between the spheres? (ke = 8.99*109 N·m2/C2)

A repelling force must occur between two charged objects under which conditions?

Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge. What happens?

Two electrons are separated by one cm. What is the ratio of the electric force to the gravitational force between them? (me = 9.11*10 - 31 kg, ke = 8.99 * 109 N.m2/C2, G = 6.67 * 10-11 N.m2/kg2, and e = 1.6 *10 - 19 C)

The charge per unit length on an insulator is . On a 2.0-m length of this material, what is the difference in the number of electrons and the number of protons?

Two point charges are 4 cm apart. They are moved to a new separation of 8 cm. By what factor does the resulting mutual force between them change?

A 6.00- μ\muμ C charge is placed at the origin and a second charge is placed on the x axis at x = 0.300 m. If the resulting force on the second charge is 6.40 N in the negative x direction, what is the force on the charge at the origin?

A 6.0-mC charge is placed at the origin and a second charge is placed on the x axis at x = 0.30 m. If the resulting force on the second charge is 5.4 N in the positive x direction, what is the value of its charge?

An electron is sent at high speed toward a gold nucleus (charge +79e) . What is the electrical force acting on the electron when it is 3.0*10 - 13 m away from the gold nucleus? (e = 1.6 *10 - 19 C, ke = 8.99 * 109 N·m2/C2)

A metallic object holds a charge of -2.9 *10-5 C. What total number of electrons does this represent? (e = 1.6 *10-19 C is the magnitude of the electronic charge.)

Two equal charges, each Q, are separated by some distance. What third charge would need to be placed half way between the two charges so that the net force on each charge would be zero?

In a thundercloud there may be an electric charge of +40 C near the top of the cloud and -40 C near the bottom of the cloud. These charges are separated by about 2.0 km. What is the electric force between these two sets of charges? (ke = 8.99 * 109 N·m2/C2)

About how many electrons are in 0.3 gram of water (H₂O) ?

Two point charges, separated by 15 cm, have charge values of +2.0 µC and -4.0 µC, respectively. What is the value of the mutual force between them? (k_e = 8.99 * 10⁹ N.m²/C²)

The constant k_e, which appears in Coulomb's law formula, is equivalent dimensionally to which of the following?

Two identical spheres each carry a charge of -40.0 µC. The spheres are separated by a distance of 2.00 m. What is the electric force between the spheres? (k_e = 8.99*10⁹ N·m²/C²)

Two electrons are separated by one cm. What is the ratio of the electric force to the gravitational force between them? (m_e = 9.1110 ^- ³¹kg, k_e = 8.99 10⁹ N.m²/C², G = 6.67 * 10^-11 N.m²/kg², and e = 1.6 *10 ^- ¹⁹ C)

A 6.00- $\mu$ C charge is placed at the origin and a second charge is placed on the x axis at x = 0.300 m. If the resulting force on the second charge is 6.40 N in the negative x direction, what is the force on the charge at the origin?

An electron is sent at high speed toward a gold nucleus (charge +79e) . What is the electrical force acting on the electron when it is 3.010 ^- ¹³ m away from the gold nucleus? (e = 1.6 10 ^- ¹⁹ C, k_e = 8.99 * 10⁹ N·m²/C²)

A metallic object holds a charge of -2.9 10^-⁵C. What total number of electrons does this represent? (e = 1.6 10^-¹⁹ C is the magnitude of the electronic charge.)

In a thundercloud there may be an electric charge of +40 C near the top of the cloud and -40 C near the bottom of the cloud. These charges are separated by about 2.0 km. What is the electric force between these two sets of charges? (k_e = 8.99 * 10⁹ N·m²/C²)