The work function for metallic magnesium is 3.68 ev. calculate the velocity in km/s for electrons ejected from a metallic magnesium surface by light of wavelength 315 nm.

v = 301.62 km/s

Explanation:

Given that:

The work function of the magnesium = 3.68 eV

Energy in eV can be converted to energy in J as:

1 eV = 1.6022 × 10⁻¹⁹ J

So, work function =

Using the equation for photoelectric effect as:

Also,

Applying the equation as:

Where,  

h is Plank's constant having value

c is the speed of light having value

m is the mass of electron having value

is the wavelength of the light being bombarded

v is the velocity of electron

Given,

Thus, applying values as:

v = 3.0162 × 10⁵ m/s

Also, 1 m = 0.001 km

So, v = 301.62 km/s

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