Work functions of caesium and lead are 2.14 eV and 4.25 eV respectively.
Which of the two has a higher threshold wavelength ?

Explanation

To determine which of the two metals, caesium or lead, has a higher threshold wavelength based on their work functions, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Work Function**: The work function (Φ) is the minimum energy required to eject an electron from a metal surface. It is measured in electron volts (eV).

2. **Given Values**:
- Work function of caesium (Φ_Cs) = 2.14 eV
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