Question 1

Two uniform rods, each of length 2.0 m, are bent to form semicircles. One rod has a charger per unit lent of 1.5 nC/m, and the other has a charge per unit length of -1.5 nC/m. The semicircles are joined to make a circle. What is the magnitude of the electric field at the center of the circle?

Accepted Answer

The answer of Two uniform rods, each of length 2.0...

Question 2

Imagine for a minute that the Moon is held in its orbit about the Earth by electrical forces rather than by gravitation. What electrical charges −Q on the Earth and +Q on the Moon are necessary to hold the Moon in a circular orbit with a period of 27.3 days? The Earth-Moon distance is 384 000 km and the mass of the Moon is 7.35 × 10²² kg.

Accepted Answer

The answer of Imagine for a minute that the Moon...

Question 3

In a diagram of charges and electric field lines charge  has twelve field lines going outward from it and charge  has three field lines going into it. If one of the charges is 100 nC, what is the other one?

Accepted Answer

The number of field lines going out from or into a charge is directly proportional to the charge. Since one charge has 12 field lines going outward while the other has only 3 going inward, the charge with 12 field lines must be larger. Therefore, it is not possible for the larger charge to be 100 nC. The only option left is for the larger charge to be -100 nC, and the smaller charge to be 25 nC. This configuration would result in 12 field lines going out from the positive charge and 3 going into the negative charge. Therefore, the answer is choice C, -25 nC (the smaller charge with 3 field lines going into it).

Question 4

Suppose a uniform electric field of 4 N/C is in the positive x direction. When a charge is placed at and fixed to the origin, the resulting electric field on the x axis at x = 2 m becomes zero. What is the magnitude of the electric field at x = 4 m on the x axis at this time?

Accepted Answer

The charge at the origin creates an electric field that cancels the uniform field at x = 2 m. This means the charge's field is -4 N/C at x = 2 m. The field from a point charge decreases with the square of the distance, so at x = 4 m, it will be -1 N/C. The uniform field is 4 N/C, so the net field is 4 N/C - 1 N/C = 3 N/C.

Question 5

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−³¹ kg, charge = 1.60 × 10−¹⁹ C) from rest to 3.00 × 10⁷ m/s within a distance of 2.00 cm. What electric field is required?

Accepted Answer

The answer of The electron gun in a television tube...

Question 6

A proton moving at 3 × 10⁴ m/s is projected at an angle of 30° above a horizontal plane. If an electric field of 400 N/C is directed downwards, how long does it take the proton to return to the horizontal plane? (HINT: Ignore gravity.) [m_Proton = 1.67 × 10−²⁷ kg, q_Proton = +1.6 × 10−¹⁹ C.]

Accepted Answer

The answer of A proton moving at 3 × 10⁴...

Question 7

An alpha particle (charge = +2e) is sent at high speed toward a gold nucleus (charge +79e). What is the electrical force acting on the alpha particle when it is at a distance of 2 × 10−¹⁴ m away from the gold nucleus? (e = 1.6 × 10−¹⁹ C)

Accepted Answer

The answer of An alpha particle (charge = +2e) is...

Quiz 23: Electric Fields

Two uniform rods, each of length 2.0 m, are bent to form semicircles. One rod has a charger per unit lent of 1.5 nC/m, and the other has a charge per unit length of -1.5 nC/m. The semicircles are joined to make a circle. What is the magnitude of the electric field at the center of the circle?

In a diagram of charges and electric field lines charge has twelve field lines going outward from it and charge has three field lines going into it. If one of the charges is 100 nC, what is the other one?

Suppose a uniform electric field of 4 N/C is in the positive x direction. When a charge is placed at and fixed to the origin, the resulting electric field on the x axis at x = 2 m becomes zero. What is the magnitude of the electric field at x = 4 m on the x axis at this time?

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−31 kg, charge = 1.60 × 10−19 C) from rest to 3.00 × 107 m/s within a distance of 2.00 cm. What electric field is required?

A proton moving at 3 × 104 m/s is projected at an angle of 30° above a horizontal plane. If an electric field of 400 N/C is directed downwards, how long does it take the proton to return to the horizontal plane? (HINT: Ignore gravity.) [mProton = 1.67 × 10−27 kg, qProton = +1.6 × 10−19 C.]

An alpha particle (charge = +2e) is sent at high speed toward a gold nucleus (charge +79e). What is the electrical force acting on the alpha particle when it is at a distance of 2 × 10−14 m away from the gold nucleus? (e = 1.6 × 10−19 C)

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−³¹ kg, charge = 1.60 × 10−¹⁹ C) from rest to 3.00 × 10⁷ m/s within a distance of 2.00 cm. What electric field is required?

An alpha particle (charge = +2e) is sent at high speed toward a gold nucleus (charge +79e). What is the electrical force acting on the alpha particle when it is at a distance of 2 × 10−¹⁴ m away from the gold nucleus? (e = 1.6 × 10−¹⁹ C)