Question

Which type of glass is commonly used for optical lenses?

• A. Alumino-silicate glass
• B. Lead glass
• C. Borosilicate glass
• D. Laminated glass

Hint:

Lead glass is used in optical applications because lead oxide increases refractive index and improves optical properties.

Answer 1

The Correct Option is B

Optical lenses require glass with special optical properties. Important properties for optical lenses are: \[ \text{high refractive index,} \] \[ \text{good transparency,} \] \[ \text{good polishability,} \] and \[ \text{controlled dispersion.} \] Lead glass contains lead oxide: \[ PbO. \] Lead oxide increases the refractive index of glass. Because of this, lead glass can bend light more effectively than ordinary glass. This makes it suitable for optical lenses, prisms, and other optical components. Borosilicate glass is mainly used for laboratory ware and heat-resistant glass. Alumino-silicate glass is used where high strength and thermal resistance are needed. Laminated glass is mainly used for safety purposes such as windshields. Therefore, the glass commonly used for optical lenses is: \[ \text{Lead glass}. \]