Question

The red light of a wavelength $6400 \, Å$ in the air has a wavelength of $4000 \, Å$ in glass. If the wavelength of violet light in air is $4400 \, Å$ , then the wavelength in the glass is

• A. $2570Å$
• B. $2750Å$
• C. $1600Å$
• D. $2510Å$

Answer 1

Answer: (B)

$\left(\mu \right)_{g}=\frac{\left(\left(\lambda \right)_{r}\right)_{air}}{\left(\left(\lambda \right)_{r}\right)_{glass}}=\frac{6400}{4000}=1.6$
Now, $\left(\mu \right)_{g}= \, \frac{\left(\left(\lambda \right)_{v}\right)_{air}}{\left(\left(\lambda \right)_{v}\right)_{glass}}$
$\left(\left(\lambda \right)_{v}\right)_{glass}=\frac{\left(\left(\lambda \right)_{v}\right)_{air}}{\left(\mu \right)_{g}}=\frac{4400}{1 .6}=2750Å$