Why caesium and potassium are used as electrodes in photoelectric cells ?

Explanation

### Step-by-Step Text Solution:

1. **Understanding Photoelectric Cells**:
- A photoelectric cell is a device that converts light energy into electrical energy. It consists of two electrodes: a cathode and an anode. The cathode is photosensitive, meaning it can emit electrons when exposed to light.

2. **Role of the Cathode**:
- When light strikes the cathode, it provides enough energy to eject electrons from the material. This process is known as the photoelectric effect. The emitted electrons then flow towards the anode, which captures them.

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