How many photons are produced in a laser pulse of 0.500 J at 661 nm?
To determine the number of photons produced in a laser pulse of 0.500 J at 661 nm, we need to use the formula:
E = N * h * c / λ,
where:
- E is the energy of the laser pulse,
- N is the number of photons,
- h is Planck's constant (6.626 x 10^-34 J·s),
- c is the speed of light (approx. 3 x 10^8 m/s),
- λ is the wavelength of the laser light.
First, let's convert the energy from joules to electronvolts (eV), as photon energies are commonly expressed in electronvolts (1 eV = 1.602 x 10^-19 J):
Energy (eV) = Energy (J) / (1.602 x 10^-19 J/eV).
Plugging in the given energy, we have:
Energy (eV) = 0.500 J / (1.602 x 10^-19 J/eV).
Next, we can calculate the energy of one photon using the formula:
Energy (eV/photon) = Energy (eV) / N.
Since we are trying to find N (the number of photons), rearranging the equation gives us:
N = Energy (eV) / Energy (eV/photon).
Finally, we need to calculate the energy of one photon using the formula:
Energy (eV/photon) = h * c / λ,
where h, c, and λ are constants given earlier.
Plug in the values and solve for N:
Energy (eV/photon) = (6.626 x 10^-34 J·s) * (3 x 10^8 m/s) / (661 x 10^-9 m).
After getting the value of Energy (eV/photon), divide the Energy (eV) obtained earlier by Energy (eV/photon) to find the number of photons (N) produced in the laser pulse.