Answer
See explanation.
Work Step by Step
a, i. First evaluate $\frac{eV}{kT}$ for the given voltage and temperature.
$\frac{(1.6\times10^{-19}C)(0.00100V)}{(1.381\times10^{-23}J/K)(290K)}=0.0400$
Now find the current at this temperature using equation 42.22 and the given saturation current.
$I=(0.500mA)(e^{eV/kT}-1)=0.0204 mA$
ii. Repeat the calculation using this voltage, to find a current of -0.0196 mA.
iii. Repeat the calculation using this voltage, to find a current of 26.8 mA.
iv. Repeat the calculation using this voltage, to find a current of -0.491 mA.
b. For very small voltages, the current and voltage are approximately proportional.