# Wavelength (nm), Frequency (THz), and Energy (eV) calculator

The following calculator calculates the wavelength in nm to the frequency in THz, the wavelength to energy in eV, frequency in THz to wavelength in nm, frequency in THz to energy in eV, energy in eV to wavelength in nm, and energy in eV to frequency in THz.

## Important instructions

• Only one value of wavelength (in nm), frequency (in THz), or energy (in eV) is required to calculate the remaining two values.
• Press the calculate button after inserting the value.
• Reset the calculator after each calculation.
• A visualization of an EM wave traveling at the speed of light and having a particular wavelength is provided in Fig. 1.

## Formulas employed in the calculations

The frequency (f) and wavelength (λ) are related to each other through the speed of light (c) by the following relation (Eq. 1).

$c=f\lambda\hspace{5cm}(1)$

The energy (E) in joules and frequency are related to each other through following formula (Eq. 2).

$E=hf\hspace{5cm}(2)$

Where, h is the Planck’s constant with a value of 6.62607004 × 10-34 m2kg/s. In order to find the relation between energy and wavelength, the value of frequency from Eq. 1 can be substituted in Eq. 2. The relation between wavelength and energy is shown in Eq. 3.

$E=\frac{hc}{\lambda}\hspace{5cm}(3)$

The calculated energy from the above relations is in joules. In order to calculate the energy in eV (which is the units in which the energy is calculated in the given calculator), the calculated energy can be divided by the charge of an electron (has a value of 1.60217662 × 10-19 coulombs).

$E (eV)=\frac{hc}{\lambda e}\hspace{5cm}(3)$

The calculated wavelength has the units of nanometers (nm), which can be converted into other units by following conversions.

• 1 nm = 10-9 m (meters)
• 1 nm = 10-7 cm (centimeters)
• 1 nm = 10-6 mm (millimeters)
• 1 nm = 10-3 μm (micrometers)
• 1 nm = 101 A (Angstroms)
• 1 nm = 3.93701×10-8 inch (inches)

The calculated frequency has the units of terahertz (THz), which can be converted into other units by following conversions.

• 1 THz = 103 GHz (gigahertz)
• 1 THz = 106 MHz (megahertz)
• 1 THz = 109 KHz (kilohertz)
• 1 THz = 1012 Hz (hertz)

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