The material having minimum work function is

Options

A. copper
B. silver
C. gold
D. cesium

Answer

To solve the question regarding which material has the minimum work function, we will follow these steps:

### Step 1: Understand the Concept of Work Function
The work function (φ) is defined as the minimum energy required to remove an electron from the surface of a material. It is typically measured in electron volts (eV).

### Step 2: Identify the Work Functions of the Given Materials
We need to compare the work functions of the following materials:
- Copper (Cu)
- Silver (Ag)
- Gold (Au)
- Cesium (Cs)

From the information provided:
- Work function of Copper (Cu) = 4.70 eV
- Work function of Silver (Ag) = 4.73 eV
- Work function of Gold (Au) = 5.1 eV
- Work function of Cesium (Cs) = 2.14 eV

### Step 3: Compare the Work Functions
Now, we will compare the work functions of all the materials listed:
- Copper: 4.70 eV
- Silver: 4.73 eV
- Gold: 5.1 eV
- Cesium: 2.14 eV

### Step 4: Determine the Minimum Work Function
From the comparison, we can see that Cesium has the lowest work function at 2.14 eV.

### Step 5: Conclusion
Therefore, the material having the minimum work function is **Cesium (Cs)**.

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