Platinum, which s widely used as a catalyst, has a work function ф (the minimum ene needed to eject an electron from the metal surface) of 9.05 x 1019 j. what is the longe wavelength of light which will cause electrons to be emitted? a) 2.196 x 107 m b) 4.553 x 10-6 m c) 5.654 x 10 m ans: a d) e) 1.370 x 1015 m > 10 nm

The longest wavelength is 2.19 × 10⁻⁷ m.

Explanation:

The work function (ф) is the minimum energy required to remove an electron from the surface of a metal. The minimum frequency required in a radiation to submit such energy can be calculated with the following expression.

ф = h × ν

where,

h is the Planck's constant (6.63 × 10⁻³⁴ J.s)

ν is the threshold frequency for the metal

In this case,

We can find the wavelength associated to this frequency using the following expression.

c = λ × ν

where,

c is the speed of light (3.00 × 10⁸ m/s)

λ is the wavelength

Then,

Option (A) is the correct answer.

Explanation:

The given data is as follows.

      Work function () = J

Now, relation between work function and wavelength is as follows.

where,   h = planck's constant = Js

              c = speed pf light = m/s

            = wavelength

As work function is also known as binding energy. Therefore, putting the given values into the above formula as follows.

        J =      

                    =                

                                     =

Thus, we can conclude that long wavelength of light which will cause electrons to be emitted is .