Question

A quartz lamp with iodine vapour releases ultraviolet light which falls on a photoelectric cell. If a thick glass plate is now introduced between the lamp and photoelectric cell then:

• A. the photoelectric current increases
• B. the maximum kinetic energy of photoelectrons decreases
• C. the photoelectric current decreases
• D. the maximum kinetic energy of photoelectrons increases

Answer 1

The correct option is C the photoelectric current decreases

If a thick glass plate in introduced, speed of the light in glass will decreases so, number of light particle passing through a cross-section of glass per unit time will become less. So, intensity of the light will decrease. And we know that as intensity decreases current decreases. So, by introducing glass plate photoelectric current decreases.