Rahul conducts an experiment with a concave lens of f = –20 cm. If he placed…
2024
Rahul conducts an experiment with a concave lens of f = –20 cm. If he placed the object of height 10 cm at a distance of 30 cm from the optical centre of lens, where should the screen be placed from the optical centre to take the image on the screen?
Answer: A. He will never be able to take the image on the screen wherever the screen is placed. — A concave lens is a diverging lens, meaning it always causes incident light rays to spread out. When an object is placed in front of a concave lens, the…
- A.
He will never be able to take the image on the screen wherever the screen is placed.
- B.
The screen should be placed at a distance less than 30 cm.
- C.
The screen should be placed at a distance more than 30 cm.
- D.
The screen should be placed between 20 cm and 30 cm.
- E.
Question not attempted
Attempted by 130 students.
Show answer & explanation
Correct answer: A
A concave lens is a diverging lens, meaning it always causes incident light rays to spread out. When an object is placed in front of a concave lens, the refracted rays diverge and appear to come from a point on the same side as the object. This results in the formation of a virtual, erect, and diminished image between the optical centre and the focal point. Virtual images are formed by the apparent intersection of light rays, not actual convergence. Since a screen can only capture real images formed by the actual meeting of light rays, it is impossible to project a virtual image onto a screen. Therefore, no matter where Rahul places the screen on the other side of the lens, he will never be able to obtain a clear image. Options suggesting specific distances (B, C, D) are incorrect because they imply the formation of a real image, which does not occur with a single concave lens.