Question

A ray of blue light has a wavelength of about 4.7×10⁻⁷ m. Will exposure to blue light cause electrons to be emitted from cesium?

Answer 1

Yes

Step-by-step explanation:

Use E = hc/λ to find the Energy of blue light

h = Planck's constant

c = speed of light

E = (6.63x10⁻³⁴)(2.99x10⁸) / (4.7x10⁻⁷) ≈ 4.22 x 10⁻¹⁹J

compare this to the work function value (the minimum energy required to remove an electron from cesium) of cesium (look-up this value):

3.43 x 10⁻¹⁹J

Since 4.22 x 10⁻¹⁹J > 3.43 x 10⁻¹⁹J, then the answer is YES

Blue light has enough energy to cause the photoelectric effect in cesium