Why does a DVD store almost 30 times more inf | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) The storage capacity of an optical disc is determined by the size of the pits and lands,which is limited by the diffraction limit of the laser bea

Vedclass · Accepted Answer

$DVD$ uses a shorter-wavelength laser of $6350 \,\mathring{A}$,while a $CD$ uses an infrared laser of $7800 \,\mathring{A}$.

Vedclass · Answer

(A) The storage capacity of an optical disc is determined by the size of the pits and lands,which is limited by the diffraction limit of the laser beam used to read/write the data.According to the diffraction limit,the minimum spot size $d$ is proportional to the wavelength $\lambda$ of the laser $(d \propto \lambda)$.$A$ $DVD$ uses a red laser with a wavelength of approximately $6350 \,\mathring{A}$,whereas a $CD$ uses an infrared laser with a wavelength of $7800 \,\mathring{A}$.Since the $DVD$ laser has a shorter wavelength,it can focus on a smaller spot size,allowing for a much higher density of pits and lands on the disc surface.Consequently,a $DVD$ can store significantly more information (approximately $30$ times more) than a $CD$ of the same physical size.Therefore,option $(A)$ is the correct explanation.

Why does a $DVD$ store almost $30$ times more information than a $CD$?

Similar Questions

Diffraction effects are easier to notice in the case of sound waves than in the case of light waves because

In a diffraction pattern due to a single slit of width $a$,the first minimum is observed at an angle $30^{\circ}$ when light of wavelength $5000 \; \mathring{A}$ is incident on the slit. The first secondary maximum is observed at an angle of

Angular width of the central maximum of a diffraction pattern due to a single slit does not depend upon:

Write the thoughts expressed by Richard Feynman regarding the difference between interference and diffraction.

$A$ parallel beam of monochromatic light falls normally on a single narrow slit. The angular width of the central maximum in the resulting diffraction pattern

Vedclass Test Series

Exam Paper Generator

Online Exam Module