Question

formula of energy if wavelength is gven in angostrom

Answer 1

E = hc / (λ_Å * 10^-10) or E(eV) = 12400 / λ(Å)

Answer 2

The energy of a photon is fundamentally related to its wavelength by the Planck-Einstein relation.

The formula for the energy ($E$) of a photon is: $E = \frac{hc}{\lambda}$ where:

• $E$ is the energy of the photon (in Joules, J).
• $h$ is Planck's constant ($6.626 \times 10^{-34} \text{ J s}$).
• $c$ is the speed of light in vacuum ($3.00 \times 10^8 \text{ m/s}$).
• $\lambda$ is the wavelength of the photon (in meters, m).

If the wavelength is given in Angstroms ($\lambda_{Å}$), it must be converted to meters before being used in the formula, as $1 \text{ Angstrom (Å)} = 10^{-10} \text{ meters (m)}$. Therefore, $\lambda (\text{m}) = \lambda_{Å} \times 10^{-10}$.

Substituting this into the energy formula, we get: $E = \frac{hc}{\lambda_{Å} \times 10^{-10}}$ The energy $E$ calculated using this formula will be in Joules.

Alternatively, for calculations where energy is desired in electron volts (eV) and wavelength is given in Angstroms (Å), a convenient simplified formula can be used: $E(\text{eV}) = \frac{12400}{\lambda(\text{Å})}$ This simplified formula is derived by substituting the numerical values of $h$, $c$, and the conversion factor from Joules to electron volts ($1 \text{ eV} = 1.602 \times 10^{-19} \text{ J}$) into the fundamental equation.