Exam 21: Electric Charge

Charge is distributed on the surface of a spherical conducting shell. A point particle with charge q is inside. If polarization effects are negligible the electrical force on the particle q is greatest when:

Two particles, X and Y, are 4 m apart. X has a charge of 2Q and Y has a charge of Q. The force on X to that on Y is:

A charge Q is spread uniformly along the circumference of a circle of radius R. A point particlewith charge q is placed at the center of this circle. The total force exerted on the particle q can be calculated by Coulomb's law:

A particle with a charge of 5*10^-6 C and a mass of 20 g moves uniformly with a speed of 7 m/s in a circular orbit around a stationary particle with a charge of -5 *10^-6 C. The radius of the orbit is:

A wire contains a steady current of 2 A. The number of electrons that pass a cross section in 2 s is:

Two identical charges, 2.0 m apart, exert forces of magnitude 4.0 N on each other. The value of either charge is:

To make an uncharged object have a positive charge:

A charged insulator can be discharged by passing it just above a flame. This is because the flame:

A neutral metal ball is suspended by a string. A positively charged insulating rod is placed near the ball, which is observed to be attracted to the rod. This is because:

A particle with charge Q is on the y axis a distance a from the origin and a particle with charge q is on the x axis a distance d from the origin. The value of d for which the x component of the force on the second particle is the greatest is:

Two particles A and B have identical charge Q. For a net force of zero to be exerted on a third chargeparticle it must be placed:

Two particles, each with charge Q, and a third particle, with a charge q, are placed at the vertices of an equilateral triangle as shown. The total force on the particle with charge q is:

Consider the following procedural steps: To charge an electroscope by induction, use the sequence:

Two small charged objects repel each other with a force F when separated by a distance d. If the charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to d/2 the force becomes:

A positively charged insulating rod is brought close to an object that is suspended by a string. If the object is repelled away from the rod we can conclude:

Charge is distributed uniformly on the surface of a spherical balloon (an insulator). A point particle with charge q is inside. The electrical force on the particle q is greatest when:

Two uncharged metal spheres, L and M, are in contact. A negatively charged rod is brought close to L, but not touching it, as shown. The two spheres are slightly separated and the rod is then withdrawn. As a result:

A coulomb is the same as:

The magnitude of the total negative charge on the electrons in 1 mol of helium (atomic number 2, atomic mass 4) is:

Particles 1, with charge q₁ and 2, with a charge q₂ are on the x axis, with particle 1 at x = a with and particle 2 at x = -2a. For the net force on a third charged particle, at the origin to be zero q₁ and q₂ must be related by q₂=: