Concepts Of Physics MCQ Edition [Volume 1]
- Exam
- Concepts Of Physics MCQ Edition [Volume 1]
- Subject
- Physics
- Chapter
- Geometrical Optics
Concepts Of Physics MCQ Edition [Volume 1] · Physics · Geometrical Optics
A parallel beam of light strikes a converging lens parallel to its...
A parallel beam of light strikes a converging lens parallel to its principal axis. As a person moves away from the lens along the principal axis on the opposite side, the intensity of the light
Options
- Acontinuously decreases
- Bremains constant
- Cfirst increases and then decreases
- Dcontinuously increases
Correct answer
C. first increases and then decreases
Step-by-step solution
When a parallel beam of light passes through a converging lens, it converges at the principal focus.
The intensity of light is given by the power per unit area, .
As the person moves away from the lens and approaches the focus, the cross-sectional area of the converging beam decreases. This causes the intensity of light to increase, reaching a maximum at the focal point.
As the person moves beyond the focus, the light beam diverges. The cross-sectional area of the beam increases, which causes the intensity to decrease continuously.
Therefore, the intensity of light first increases and then decreases.
The intensity of light is given by the power per unit area, .
As the person moves away from the lens and approaches the focus, the cross-sectional area of the converging beam decreases. This causes the intensity of light to increase, reaching a maximum at the focal point.
As the person moves beyond the focus, the light beam diverges. The cross-sectional area of the beam increases, which causes the intensity to decrease continuously.
Therefore, the intensity of light first increases and then decreases.