Question

Determine the wavelengths for Potassium (violet, λ = 400 nm) and Strontium (red, λ = 700 nm) light emissions. Calculate the frequencies (c = wavelength × frequency) and the energy (E = h × frequency) for each.

Answer 1

Explanation:

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Answer 2

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