Question 216: Dual Nature of Matter and Radiation

Question

The work function of  a substance is $$4.0$$ $$eV.$$ The longest wavelength of light that can cause photo-electron emission from this substance is approximately.

Accepted Answer

For the longest wavelength to emit photo electron
$${{hc} \over \lambda } = \phi  \Rightarrow \lambda  = {{hc} \over \phi }$$
$$ \Rightarrow \lambda  = {{6.63 	imes {{10}^{ - 34}} 	imes 3 	imes {{10}^8}} \over {40 	imes 1.6 	imes {{10}^{ - 16}}}} = 310nm$$

Answer

$$310$$ $$nm$$

Answer

$$400$$ $$nm$$

Answer

$$540$$ $$nm$$

Answer

$$220$$ $$nm$$

Dual Nature of Matter and Radiation

The work function of a substance is $4.0 eV.$ The longest wavelength of light that can cause photo-electron emission from this substance is approximately.

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