Exam 20: Electric Fields and Forces

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?

As shown in the figure, charge q₁ = 2.2 x $10 ^ { - 6 }$ C is placed at the origin and charge $q _ { 2 } = - 3.30 \times 10 ^ { - 6 } \mathrm { C }$ is placed on the $x \text {-axis, }$ at $x = - 0.200 \mathrm {~m} .$ Where along the x-axis can a third charge Q = -8.30 × 10^-6 C be placed so that the resultant force on Q is zero?

Three point charges are placed on the x-axis, as follows. A charge of +2.0 ?C is at the origin, a charge of -2.0 ?C is at x = 50 cm, and a charge of +4.0 ?C is at x = 100 cm. What are the magnitude and direction of the electrostatic force on the charge at the origin due to the other two charges? (k = 1/4??₀ = 9.0 × 10⁹ N ? m²/C²)

A particle of charge +2q is placed at the origin and particle of charge -q is placed on the x-axis at x = 2a. Where on the x-axis can a third positive charge be placed so that the net electric force on it is zero?

The force of attraction that a -40.0 μC point charge exerts on a +108 μC point charge has magnitude 4.00 N. How far apart are these two charges? (k = 1/4πε₀ = 8.99 × 10⁹ N ∙ m²/C²)

Two stationary point charges q₁ and q₂ are shown in the figure along with a sketch of some field lines representing the electric field produced by them. What can you deduce from the sketch?

What is the charge on 1.0 kg of protons?(e = 1.60 × 10^-19 C, m_proton = 1.67 × 10^-27 kg)

A proton is located at the point (x = 1.0 nm, y = 0.0 nm)and an electron is located at the point $( x = 0.0 \mathrm {~nm} ,$ $y = 4.0 \mathrm {~nm} )$ Find the magnitude of the electrostatic force that each one exerts on the other. (k = 1/4??₀ = 9.0 × 10⁹ N ? m²/C², e = 1.6 × 10^-19 C

Three identical 3.0-µC charges are placed at the vertices of an equilateral triangle that measures 30 cm on a side. What is the magnitude of the electrostatic force on any one of the charges? (k = 1/4πε₀ = 9.0 × 10⁹ N ∙ m²/C²)

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

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

Which one of the arrows shown in the figure best represents the direction of the electric field between the two uniformly charged metal plates?

A proton is placed in an electric field of intensity 800 N/C. What are the magnitude and direction of the acceleration of the proton due to this field? (e = 1.60 × 10^-19 C, m_proton = 1.67 × 10^-27 kg)

A particle with a charge of +4.0 μC has a mass of 5.0 g. What magnitude electric field directed upward will exactly balance the weight of the particle?

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. An electron is projected from plate A, directly toward plate B, with an initial speed of v₀ = 2.0 × 10⁷ m/s. What is the speed of the electron as it strikes plate B? (e = 1.6 × 10^-19 C, m_electron = 9.11 × 10^-31 kg)

What is the magnitude of the electric field 2.8 cm from a tiny object that carries an excess charge of -16 nC? (k = 1/4πε₀ = 9.0 × 10⁹ N ∙ m²/C²)

In outer space, a positive charge q is released near a positive fixed charge Q, as shown in the figure. As q moves away from Q, what is true about the motion of q? (There may be more than one correct choice.)

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?

Two tiny particles having charges of +5.00 μC and +7.00 μC are placed along the x-axis. The +5.00-µC particle is at x = 0.00 cm, and the other particle is at x = 100.00 cm. Where on the x-axis must a third charged particle be placed so that it does not experience any net electrostatic force due to the other two particles?

A solid aluminum cube rests on a wooden table in a region where a uniform external electric field is directed straight upward. What can we say concerning the charge on the top surface of the cube?