Answer
14 V
Work Step by Step
Using the current–voltage graph in figure 29–30, we deduce that a 14-mA current corresponds to a voltage of about 0.69 V across the diode.
The battery voltage is the sum of the voltages across the diode and across the resistor. The latter is found by Ohm’s Law.
$$V_{battery}=V_{diode}+V_R$$
$$=0.69V+(0.014A)(960 \Omega)=14 V$$
