题目

Foxes and farmers have never got on well. These small dog-like animals have long been accused of killing farm animals. They are officially considered as harmful and farmers try to keep their numbers down by shooting or poisoning them. Farmers can also call on the services of their local hunt to control the fox population. Hunting consists of running after a fox across the countryside, with a group of specially trained dogs, followed by men and women riding horses. When the dogs eventually catch the fox they kill it or a hunter shoots it. People who take part in hunting think of it as 如图甲所示为一测量硫化镉光敏电阻特性的实验电路，电源电压恒定，电流表内阻不计，开关闭合后，调节滑动变阻器滑片，使小灯泡发光逐渐增强，测得流过电阻的电流和光强的关系曲线如图乙所示，试根据这一特性设计一个自动光控电路。