Physics

Problem

\lambda_{\text{Cu}}

is the wavelength of

K_{\alpha}

X-ray line of copper (atomic number 29) and

\lambda_{\text{Mo}}

is the wavelength of the

K_{\alpha}

X-ray line of molybdenum (atomic number 42), then the ratio

\lambda_{\text{Cu}}/\lambda_{\text{Mo}}

is close to (a) 1.99 (b) 2.14 (c) 0.50 (d) 0.48