Suppose $0.420 \mathrm{~mol}$ of an ideal gas is isothermally and reversibly expanded in the four situations given below. What is the change in the entropy of the gas for each situation?

After the large eruption of Mount St. Helens in 1980, gas samples from the volcano were taken by sampling the downwind gas plume. The unfiltered gas samples were passed over a gold-coated wire coil to absorb mercury $(\mathrm{Hg})$ present in the gas. The mercury was recovered from the coil by heating it, and then analyzed. In one particular set of experiments scientists found a mercury vapor level of $1800 \mathrm{ng}$ of $\mathrm{Hg}$ per cubic meter in the plume, at a gas temperature of $10^{\circ} \mathrm{C}$. Calculate

The number of $\mathrm{Hg}$ atoms per cubic meter in the gas

Consider a circuit with transistor parameters described in previous problem. Determine the maximum undistorted swing in the output current $i_C$ if the total instantaneous collector current is $i_C \geq 0.1 \mathrm{~mA}$ and the total instantaneous $\mathrm{C}-\mathrm{E}$ voltage is in the range $1 \leq v_{C E} \leq 21 \mathrm{~V}$.

Repeat previous mentioned problem for the common-base circuit. Assume $V_{E B}($ on $)=0.7$ for the pnp transistor. The remaining transistor parameters are the same as mentioned before.

Gas is contained in an $8.0$-L vessel at a temperature of $20^{\circ} \mathrm{C}$ and a pressure of $9.0 \mathrm{~atm}$. (a) Determine the number of moles of gas in the vessel.

A collector-feedback circuit uses an $n p n$ transistor with $V_{\mathrm{CC}}=12 \mathrm{~V}, R_{\mathrm{C}}=1.2 \mathrm{k} \Omega$, and $R_{\mathrm{B}}=47 \mathrm{k} \Omega$. Determine the collector current and the collector voltage if $\beta_{\mathrm{DC}}=200$.

Consider a Wilson current-source circuit. Assume the reference current is $0.25 \mathrm{~mA}$ and assume transistor parameters of $V_{B E}$ (on ) $=0.7 \mathrm{~V}, \beta=100$, and $V_A=100 \mathrm{~V}$. (a) Determine the output resistance looking into the collector of $Q_3$. (b) What is the change in $I_O$ as the output voltage changes by $+5 \mathrm{~V}$ ?

What is the difference between open-collector and tri-state output?

Find the current that flows in a 40 -W bulb used in a common household circuit ( $V=120 \mathrm{~V}$ ). Compare this with the answer to the first part of Problem 19.

An ac collector resistance is usually several hundred kilohms

Consider a circuit . Assume $V_{B E}=V_{E B}=0.7 \mathrm{~V}$ for all transistors except $Q_5$ and let $\beta=\infty$. Determine all collector currents, and find $V_{C E 3}, V_{C E 5}$, and $V_{E C 7}$.

The Toyota Prius is a hybrid car that travels approximately 204 mi on 4 gal of gas. Find the amount of gas required for a 714-mi trip.

Which two variables are plotted on a collector characteristic curve?

A particular differential amplifier operates from an emitter current source whose output resistance is $0.5 \mathrm{M} \Omega$. What resistance is associated with each common-mode half-circuit? For collector resistors of $20 \mathrm{k} \Omega$ and $1 \%$ tolerance, what is the resulting common-mode gain for output taken (a) singleendedly? and (b) differentially?