24. Electric Force & Field; Gauss' Law

In the context of electric motors, what is the primary purpose of a commutator?

Alternators induce voltage by rotating which of the following components?

Which characteristic is common to all electrical insulators?

Estimate the net force between the CO group and the HN group shown in Fig. 21–72. The C and O have charges ± 0.40e, and the H and N have charges ±0.20e, where e = 1.6 x 10⁻¹⁹ C. [Hint: Do not include the “internal” forces between C and O, or between H and N.]

What mass of aluminum has a total nuclear charge of $1.0$ C? Aluminum has atomic number $13$.

How many electrons make up a charge of -58.0 μC?

How many electrons do you have to add to decrease the charge of an object by 16 μC?

A point charge ( m = 1.5 gram) at the end of an insulating cord of length 55 cm is observed to be in equilibrium in a uniform horizontal electric field of 9500 N/C, when the pendulum’s position is as shown in Fig. 21–79, with the charge 12 cm above the lowest (vertical) position. If the field points to the right in Fig. 21–79, determine the magnitude and sign of the point charge.

A charge Q is transferred from an initially uncharged plastic ball to an identical ball 21 cm away. The force of attraction is then 17 mN. How many electrons were transferred from one ball to the other?