91Ó°ÊÓ

Can a wire carry a current and still be neutral-that is, have a total charge of zero? Explain.

The \(I R\) drop across a resistor means that there is a change in potential or voltage across the resistor. Is there any change in current as it passes through a resistor? Explain.

Define depolarization, repolarization, and the action potential.

The power dissipated in a resistor is given by \(P=V^{2} / R\), which means power decreases if resistance increases. Yet this power is also given by \(P=I^{2} R\), which means power increases if resistance increases. Explain why there is no contradiction here.

There is a voltage across an open switch, such as in Figure. Why, then, is the power dissipated by the open switch small?

If two different wires having identical cross-sectional areas carry the same current, will the drift velocity be higher or lower in the better conductor? Explain in terms of the equation \(v_{\mathrm{d}}=\frac{I}{n q A}\), by considering how the density of charge carriers \(n\) relates to whether or not a material is a good conductor.

Given a battery, an assortment of resistors, and a variety of voltage and current measuring devices, describe how you would determine the internal resistance of the battery.

Why are two conducting paths from a voltage source to an electrical device needed to operate the device?

In cars, one battery terminal is connected to the metal body. How does this allow a single wire to supply current to electrical devices rather than two wires?

What are the advantages and disadvantages of connecting batteries in series? In parallel?