If the current gain of the transistor amplifier in Fig. 40–49 is β = i_c/i_B = 95, what value must R_c have if a 1.0-μA ac base current is to produce an ac output voltage of 0.40 V?

(III) A 120-V rms 60-Hz voltage is to be rectified with a full-wave rectifier as in Fig. 40–40, where R = 24 kΩ, and C = 35 μF. (a) Make a rough estimate of the average current. (b) What happens if C = 0.10 μF? [Hint: See Section 26–5.]

(II) An ac voltage of 120 V rms is to be rectified. Estimate very roughly the average current in the output resistor R (42 kΩ) for (a) a half-wave rectifier (Fig. 40–39), and (b) a full-wave rectifier (Fig. 40–40) without capacitor.

A zener diode voltage regulator is shown in Fig. 40–55. Suppose that R = 2.80 kΩ and that the diode breaks down at a reverse voltage of 130 V. (The current increases rapidly at this point, as shown on the far left of Fig. 40–38 at a voltage of -12V on that diagram.) The diode is rated at a maximum current of 120 mA. (a) If R_load = 21.0 kΩ, over what range of supply voltages will the circuit maintain the output voltage at 130 V? (b) If the supply voltage is 275 V, over what range of load resistance will the voltage be regulated?

One possible form for the potential energy (U) of a diatomic molecule (Fig. 40–8) is called the Morse Potential:

$U=U_0{[1-e^{-a(r-r_0)}]}^2$

(a) Show that r₀ represents the equilibrium distance and U₀ the dissociation energy.