Question 1

A negatively charged particle is moving in the +x-direction when it enters a region with a uniform electric field pointing in the +x-direction. Which graph gives its position as a function of time correctly? (Its initial position is x = 0 at t = 0.)

Accepted Answer

The answer of A negatively charged particle is moving in...

Question 2

A positively charged particle is moving in the +y-direction when it enters a region with a uniform electric field pointing in the +x-direction. Which of the diagrams below shows its path while it is in the region where the electric field exists. The region with the field is the region between the plates bounding each figure. The field lines always point to the right. The x-direction is to the right; the y-direction is up.

Accepted Answer

The answer of A positively charged particle is moving in...

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 answer of In a diagram of charges and electric...

Question 4

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 5

Two imaginary spherical surfaces of radius R and 2R respectively surround a positive point charge Q located at the center of the concentric spheres. When compared to the number of field lines N1 going through the sphere of radius R, the number of electric field lines N2 going through the sphere of radius 2R is

Accepted Answer

The answer of Two imaginary spherical surfaces of radius R...

Question 6

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 electric field at x=2m becomes zero, so we know that the electric field due to the charge at the origin must be equal in magnitude but opposite in direction to the uniform field at x=2m. Thus, the magnitude of the electric field at x=2m is 4 N/C.

At x=4m, the electric field from the charge at the origin will be weaker due to the increased distance, but it will still be in the opposite direction to the uniform field. By symmetry, we know that the field will be exactly halfway between the origin and x=2m, so the electric field at x=4m is half the electric field at x=2m: 
E = 1/2 * (4 N/C) = 2 N/C

Therefore, the answer is C.

Question 7

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 8

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 × 10⁻²⁷kg, qProton = +1.6 × 10⁻¹⁹ C.]

Accepted Answer

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

Quiz 24: Electric Fields

A negatively charged particle is moving in the +x-direction when it enters a region with a uniform electric field pointing in the +x-direction. Which graph gives its position as a function of time correctly? (Its initial position is x = 0 at t = 0.)

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?

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?

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.]

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?