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Gupta Ravi

Asked: January 6, 2025In: Class 12 Physics

A glass lens of refractive index 1.5 is placed in a trough of liquid. What must be the refractive index of the liquid in order to mark the lens disappear?

Refractive index of liquid should be 1.5. Class 12 Physics Chapter 9 Ray Optics and Optical Instruments Session 2024-2025.

Gupta Ravi

Asked: January 6, 2025In: Class 12 Physics

Two thin lenses of power – 4D and 2D are placed in contact coaxially. What is the focal length of the combination?

Here P = P₁ + P2 = (-4 D) + (2 D) = -2D Hence, f = 1/p = – 1/2 m = -50 cm. Class 12 Physics Chapter 9 Ray Optics and Optical Instruments Session 2024-2025.

Gupta Ravi

Asked: January 6, 2025In: Class 12 Physics

A convex lens is placed in contact with a plane mirror. A point object at a distance of 20 cm on the axis of this combination has its image coinciding with itself. What is the focal length of the lens?

The focal length of the given convex lens is 20 cm. Class 12 Physics Chapter 9 Ray Optics and Optical Instruments Session 2024-2025.

Gupta Ravi

Asked: January 5, 2025In: Class 12 Physics

A converging lens is kept coaxially in contact with diverging lens – both the lenses being of equal focal lengths. What is the focal length of the combination?

Let focal length of converging lens f₁ = + f and focal length of diverging lens f₂ = -f. If focal length of combination be feq, then 1/feq = 1/f1 + 1/f2 = 1/(+f) + 1/(-f) = 0 feq = ...

Gupta Ravi

Asked: January 4, 2025In: Class 12 Physics

A biconcave lens made of a transparent material of refractive index 1.25 is immersed in water of refractive index 1.33. Will the lens behave as a converging or a diverging lens ? Give reason.

The lens will now behave as a converging lens because its new refractive index w.r.t. water is less than one. Class 12 Physics Chapter 9 Ray Optics and Optical Instruments Session 2024-2025.

Load More Questions

A glass lens of refractive index 1.5 is placed in a trough of liquid. What must be the refractive index of the liquid in order to mark the lens disappear?

Two thin lenses of power – 4D and 2D are placed in contact coaxially. What is the focal length of the combination?

A convex lens is placed in contact with a plane mirror. A point object at a distance of 20 cm on the axis of this combination has its image coinciding with itself. What is the focal length of the lens?

A converging lens is kept coaxially in contact with diverging lens – both the lenses being of equal focal lengths. What is the focal length of the combination?

A biconcave lens made of a transparent material of refractive index 1.25 is immersed in water of refractive index 1.33. Will the lens behave as a converging or a diverging lens ? Give reason.

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