A 45-V battery of negligible internal resistance is connected to a 37-k$\Omega$ and a 28-k$\Omega$ resistor in series. What reading will a voltmeter, of internal resistance 100 k$\Omega$, give when used to measure the voltage across each resistor? What is the percent inaccuracy due to meter resistance for each case?

A $35~\mathrm{V}$ battery of negligible internal resistance is connected to a $44~\mathrm{k} \Omega$ and a $27~\mathrm{k} \Omega$ resistor in series. What reading will a voltmeter, of internal resistance $85 \mathrm{k} \Omega$, give when used to measure the voltage across each resistor? What is the percent inaccuracy due to meter resistance for each case?

Explain how the resistance of a lightbulb filament changes after the light has been turned on.

Briefly describe pultrusion, filament winding, and prepreg production fabrication processes; cite the advantages and disadvantages of each.

For the wire in Fig. $25-39$, whose diameter varies uniformly from $a$ to $b$ as shown, suppose a current $I=2.0 \mathrm{~A}$ enters at $a$. If $a=2.5 \mathrm{~mm}$ and $b=4.0 \mathrm{~mm}$, what is the current density (assume uniform) at each end?

An average power output of $150 \mathrm{~W}$ is sent into a $4~\Omega$ loudspeaker. What are the rms voltage and the rms current fed to the speaker at at $1.0 \mathrm{~W}$ when the volume is turned down?

A traditional incandescent lamp filament may have been lit to a temperature of $2700 \mathrm{~K}$. A contemporary halogen incandescent lamp filament may be at around $2900 \mathrm{~K}$. Estimate the percent increase in efficiency of the halogen bulb over the traditional one.

A traditional incandescent lamp filament may have been lit to a temperature of $2700 \mathrm{~K}$. A contemporary halogen incandescent lamp filament may be at around $2900 \mathrm{~K}$. To produce the same amount of light as a traditional $100 \mathrm{~W}$ bulb, estimate what wattage a halogen bulb should use.

A traditional incandescent lamp filament may have been lit to a temperature of $2700 \mathrm{~K}$. A contemporary halogen incandescent lamp filament may be at around $2900 \mathrm{~K}$. Estimate the percent improvement of the halogen bulb over the traditional one.

Can a $1.8~\mathrm{mm}$-diameter copper wire have the same resistance as a tungsten wire of the same length? Give numerical details.

Can a $2.2-\mathrm{mm}$-diameter copper wire have the same resistance as a tungsten wire of the same length? Give numerical details.

Can a 2.5-mm-diameter copper wire have the same resistance as a tungsten wire of the same length? Give numerical details.

Three 240-$\Omega$ resistors can be connected together in four different ways, making combinations of series and/or parallel circuits. What are these four ways and what is the net resistance in each case?

Compact "ultracapacitors" with capacitance values up to several thousand farads are now commercially available. One application for ultracapacitors is in providing power for electrical circuits when other sources (such as a battery) are turned off. To get an idea of how much charge can be stored in such a component, assume a 1200-F ultracapacitor is initially charged to $12.0 \mathrm{~V}$ by a battery and is then disconnected from the battery. If charge is then drawn off the plates of this capacitor at a rate of $1.0 \mathrm{mC} / \mathrm{s}$, say, to power the backup memory of some electrical gadget, how long (in days) will it take for the potential difference across this capacitor to drop to $6.0 \mathrm{~V}$ ?