Answer:
For Potassium:
Frequency = 7.5 x 10¹⁴ Hz; E (energy) = 8.83 x 10⁻²¹ J
For Strontium:
Frequency = 4.3 x 0¹⁴ Hz
E (energy) = 2.85 x 10⁻¹⁹ J
Explanation:
Wavelength is represented by λ, and Frequency is represented by ν .
E (energy) = hν = hc/λ, where ν = frequency; c = speed of light = 3 x 10⁸ m/s; 1 s-1 = 1 Hz
h = planck's constant = 6.62 x 10⁻³⁴ J.s; 1 nm = 10⁻⁹ m
1. Potassium λ (wavelength) = 400 nm, Frequency, ν is given by :
ν = c/λ = (3 x 10⁸ m/s) / 400 nm
= (3 x 10⁸ m/s) / 400 x 10⁻⁹ s-1
= 0.0075 x 10¹⁷s-1
= 7.5 x 10¹⁴ s-1
Frequency = 7.5 x 10¹⁴ Hz
E (energy) = hν = (6.62 x 10⁻³⁴ J.s) x (7.5 x 10¹⁴s-1)
E (energy) = 8.83 x 10⁻²¹ J
2. Strontium λ (wavelength) = 700 nm ,Frequency, ν is given by :
ν = c/λ = (3 x 10⁸ m/s) / 700 nm
= (3 x 10⁸ m/s) / 700 x 10⁻⁹s-1
= 0.00428571428 x 10¹⁷s-1
= 4.3 x 10¹⁴ s-1
Frequency = 4.3 x 0¹⁴ Hz
E (energy) = hν = (6.62 x 10⁻³⁴ J.s) x (4.3 x 0¹⁴s-1)
E (energy) = 2.85 x 10⁻¹⁹ J
