A photographic film is coated with a silver bromide layer. When light falls on this film, silver bromide molecules dissociate and the film records the light there. A minimum of 0.6e V is needed to dissociated a silver bromide molecule. Find the maximum wavelength of light that can be recorded by the film.
Correct option is A. 2071
$$w_0=0.6ev$$
For $$w_0$$ to be min $$'\lambda '$$ becomes maximum.
The wok function is given as:
$$w_0=\dfrac { hc }{ \lambda } $$
or $$\lambda=\dfrac { hc }{ { w }_{ 0 } } $$
Substitute the values in above expression.
$$=\dfrac { 6.63\times { 10 }^{ -34 }\times 3\times { 10 }^{ 8 } }{ 0.6\times 1.6\times { 10 }^{ -19 } } $$
$$= 20.71\times10^{-7}m=2071nm$$