Question

a uv light with a wavelength of 250. nm is shone on the silver surface. what is the incident energy from the light?
$e_{i} = ? \times 10^{?}$ j

Explanation:

Step1: Convert wavelength to meters

$\lambda = 250. \text{ nm} = 250. \times 10^{-9} \text{ m} = 2.50 \times 10^{-7} \text{ m}$

Step2: Use photon energy formula

The formula for photon energy is $E = \frac{hc}{\lambda}$, where $h = 6.626 \times 10^{-34} \text{ J·s}$ (Planck's constant) and $c = 3.00 \times 10^8 \text{ m/s}$ (speed of light).

$$ E = \frac{(6.626 \times 10^{-34}) \times (3.00 \times 10^8)}{2.50 \times 10^{-7}} $$

Step3: Calculate numerator first

$(6.626 \times 10^{-34}) \times (3.00 \times 10^8) = 1.9878 \times 10^{-25}$

Step4: Divide by wavelength

$E = \frac{1.9878 \times 10^{-25}}{2.50 \times 10^{-7}} = 7.9512 \times 10^{-19}$

Step5: Round to 3 significant figures

$E \approx 7.95 \times 10^{-19}$

Answer:

$E_I = 7.95 \times 10^{-19} \text{ J}$