Calculate the threshold freqency of the metalfrom the photoelectronsare emitted with zero velocity when exposed to radiation of wavelength 6800 `Å`
Hint `: KE = (1)/(2) mv^(2)`
`hv= hv_(0) + KE, KE=0`
`v= (c ) /( lambda)`

Explanation

To calculate the threshold frequency of the metal from which photoelectrons are emitted with zero velocity when exposed to radiation of wavelength 6800 Å, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Threshold Frequency**:
- The threshold frequency (ν₀) is the minimum frequency required to emit a photoelectron from a metal surface. When the energy of the incoming radiation is equal to the work function of the metal, the photoelectron is emitted with zero kinetic energy.

2. **Use the Photoelectric Equation**:
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