What is the resistance of a photo cell when exposed to light?

The resistance of a photo cell, also known as a light-dependent resistor (LDR), varies significantly based on the intensity of light it is exposed to. When exposed to light, the resistance of a photo cell generally decreases. In bright light conditions, the resistance can be in the region of a few hundred ohms. Therefore, a photo cell commonly has a resistance around 1000 ohms when adequately illuminated, which corresponds to the choice given.

In contrast, in low light conditions, the resistance can increase dramatically, sometimes reaching values in the megohm range. Thus, while 1 megohm might be the resistance in darkness, it does not accurately represent the situation when light is present. The figure of 100 ohms is on the lower end of what might be encountered in some situations but does not typically apply to most practical applications of photo cells under normal lighting. The value of 10,000 ohms generally reflects a resistance more characteristic of ambient light conditions rather than direct exposure to bright light.

Overall, the value of 1000 ohms aligns well with the expected operational range of photo cells under light exposure, which helps explain the choice confidently.