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प्रश्न
Choose the correct alternative and rewrite the following:
Inside water, an air bubble behaves ....................
पर्याय
always like a flat plate
always like a concave lens
always like a convex lens
always like a concave mirror
उत्तर
always like a concave lens
- Inside water, the air bubble behaves like a Concave lens. The concave lenses are known as diverging lenses as the rays diverge after falling on the concave lens.
- The concave lens diverges a straight light beam coming from the source to a diminished, upright, virtual image and forms both real and virtual images.
- The air bubble is a sphere with a convex surface and when light reaches it, the light is reflected within the water as in a concave lens.
The refractive index of air = 1 and
The index of water = 1.33.
Since the water refractive index is greater than air, the air bubbles in the water will behave like a concave lens.
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संबंधित प्रश्न
List some things that concave lens and concave mirror have in common.
Which type of lenses are:
thinner in the middle than at the edges?
What type of image is always made by a concave lens?
Things always look small on viewing through a lens. What is the nature of the lens?
Give the position, size and nature of image of formed by a concave lens when the object is placed:
at infinity.
With the help of a diagram, explain why the image of an object viewed through a concave lens appears smaller and closer than the object.
How would a pencil look like if you saw it through
a concave lens Is the image real or virtual?
An object is placed 10 cm from a lens of focal length 5 cm. Draw the ray diagrams to show the formation of image if the lens is diverging.
Which of the following can form a virtual image which is always smaller than the object?
(a) a plane mirror
(b) a convex lens
(c) a concave lens
(d) a concave mirror
A concave lens of 20 cm focal length forms an image 15 cm from the lens. Compute the object distance.
Only one of the following applies to a concave lens. This is:
(a) focal length is positive
(b) image distance can be positive or negative
(c) height of image can be positive or negative
(d) image distance is always negative
Name one of the common defects of vision and the type of lens used to remove it.
Complete the following sentence:
A short-sighted person cannot see ............ objects clearly. Short-sightedness can be corrected by using ........... lenses.
A person cannot see distant objects clearly. His vision can be corrected by using the spectacles containing:
(a) concave lenses
(b) plane lenses
(c) contact lenses
(d) convex lenses
Express power of a concave lens of focal length 50 cm with its sign.
When an object is kept within the focus of a concave mirror, an enlarged image is formed behind the mirror. This image is :
Draw images in case of a concave lens when the object is at infinity.
