27. Resistors & DC Circuits

Which of the following is always true about capacitors and batteries?

A wire is connected to the positive and negative plates of a capacitor. Electrons in the wire feel an attraction toward the positive plate of a capacitor, and a repulsion from the negative plate. What is true about the motion of these electrons?

An aluminum wire consists of the three segments shown in FIGURE P27.64. The current in the top segment is 10 A. For each of these three segments, find the b. Current density J. Place your results in a table for easy viewing.

Lightning occurs when there is a flow of electric charge (principally electrons) between the ground and a thundercloud. The maximum rate of charge flow in a lightning bolt is about 20,000 C/s; this lasts for 100 ms or less. How much charge flows between the ground and the cloud in this time? How many electrons flow during this time?

A linear accelerator uses alternating electric fields to accelerate electrons to close to the speed of light. A small number of the electrons collide with a target, but a large majority pass through the target and impact a beam dump at the end of the accelerator. In one experiment the beam dump measured charge accumulating at a rate of −2.0 nC/s. How many electrons traveled down the accelerator during the 2.0 h run?

Which of the following best describes how a switch functions in an electrical circuit?