# How to calculate wavelength from energy

Understanding the relationship between energy and wavelength is essential in various fields like physics, chemistry, and engineering. The connection between these two properties is described by the Planck’s equation. In this article, we will discuss how to calculate the wavelength of a photon or particle given its energy.

**Step 1: Understand the basic concepts**

Before we begin calculations, it’s essential to comprehend the concepts of wavelength and energy. Wavelength (λ) is the distance between two consecutive points in a wave, usually measured in meters (m). Energy (E), on the other hand, typically refers to the energy of photons or particles in motion, measured in Joules (J).

**Step 2: Familiarize yourself with Planck’s equation**

Planck’s equation is useful for calculating a photon’s energy given its frequency or wavelength. The equation is written as:

**E = h × c / λ**

Where:

– E represents the energy of a photon

– h represents Planck’s constant (6.63 x 10^-34 Js)

– c represents the speed of light in vacuum (3 x 10^8 m/s)

– λ represents the wavelength of a photon

**Step 3: Rearrange Planck’s equation to solve for wavelength**

To find the wavelength when given energy, rearrange Planck’s equation by dividing both sides by (h × c). This results in:

λ = h × c / E

**Step 4: Plug in values and calculate**

Now that we have our rearranged equation for calculating wavelengths, plug in values for Planck’s constant, speed of light, and particle energy. Multiply Planck’s constant by the speed of light and divide that product by the given energy value:

λ = (6.63 × 10⁻³⁴ Js) × (3 × 10⁸ m/s) / E

Example:

Let’s say we want to determine the wavelength of a photon with an energy of 3.5 × 10^-19 J. Using our equation:

λ = (6.63 × 10⁻³⁴ Js) × (3 × 10⁸ m/s) / (3.5 × 10^-19 J)

λ ≈ 5.68 × 10^-7 m, or approximately 568 nm

In this case, the wavelength of the photon is around 568 nm.

**Conclusion:**

Calculating the wavelength from energy is simple when you understand Planck’s equation and can manipulate it to solve for wavelength. This skill is valuable in various applications across numerous scientific disciplines, enabling us to better analyze and interpret the properties of particles and waves in our world.