Answer
Verified
353.1k+ views
Hint:To solve this problem we should know about the following term.The power of a lens is defined as the reciprocal of the focal length. Lens power is measured in dioptres (D).So, when we apply a known formula we can easily calculate the focal length of the lens.
Complete step by step answer:
Focal length: The distance between the convex lens or a concave mirror and the focal point of a lens or mirror is called the focal length. It is the point where parallel rays of light meet or converge. And we know the power of the lens will be the reciprocal of the focal length.
As given \[P = - 2D\]
As we know,
$P = \dfrac{1}{f}$
Here, $P$ is power and $f$ is focal length.
So, keeping value in it. We get,
$P = \dfrac{1}{f}$
$ \Rightarrow - 2D = \dfrac{1}{f}$
By cross multiplication
$ \Rightarrow f = \dfrac{1}{{ - 2D}}$
$ \Rightarrow f = - 0.5\,m$
As, its focal length is negative. So, it will be a concave lens.Thus, the focal length of the given lens will be 0.5 m.
Hence, the correct option is C.
Note:Application of lens: Light is focused using lenses. Because concentrating light is so vital, lenses can be found in a variety of places. The lenses in people's glasses are probably the most prevalent lenses we see.If the power of the lens is negative it must be a concave lens. If positive power then it must be convex lens
Complete step by step answer:
Focal length: The distance between the convex lens or a concave mirror and the focal point of a lens or mirror is called the focal length. It is the point where parallel rays of light meet or converge. And we know the power of the lens will be the reciprocal of the focal length.
As given \[P = - 2D\]
As we know,
$P = \dfrac{1}{f}$
Here, $P$ is power and $f$ is focal length.
So, keeping value in it. We get,
$P = \dfrac{1}{f}$
$ \Rightarrow - 2D = \dfrac{1}{f}$
By cross multiplication
$ \Rightarrow f = \dfrac{1}{{ - 2D}}$
$ \Rightarrow f = - 0.5\,m$
As, its focal length is negative. So, it will be a concave lens.Thus, the focal length of the given lens will be 0.5 m.
Hence, the correct option is C.
Note:Application of lens: Light is focused using lenses. Because concentrating light is so vital, lenses can be found in a variety of places. The lenses in people's glasses are probably the most prevalent lenses we see.If the power of the lens is negative it must be a concave lens. If positive power then it must be convex lens
Recently Updated Pages
How many sigma and pi bonds are present in HCequiv class 11 chemistry CBSE
Mark and label the given geoinformation on the outline class 11 social science CBSE
When people say No pun intended what does that mea class 8 english CBSE
Name the states which share their boundary with Indias class 9 social science CBSE
Give an account of the Northern Plains of India class 9 social science CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Trending doubts
Difference Between Plant Cell and Animal Cell
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE
Which are the Top 10 Largest Countries of the World?
One cusec is equal to how many liters class 8 maths CBSE
Give 10 examples for herbs , shrubs , climbers , creepers
The mountain range which stretches from Gujarat in class 10 social science CBSE
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths