15.7323232 in pa form find the value of p+q
Answers
Step-by-step explanation:
\huge {\underline{\pink{Given:-}}}
Given:−
Object distance , u = -60 cm
Image distance ,v = 30cm
\huge {\underline{\green{To Find:-}}}
ToFind:−
Focal length ,f
\huge {\underline{\blue{Solution:-}}}
Solution:−
Firstly we calculate the focal length of the lens.
By using lens formula
• 1/v -1/u = 1/f
where,
v is the image distance
u is the object distance
f is the focal length
Substitute the value we get
➺ 1/30 - 1/(-60) = 1/f
➺ 1/f = 1/30 + 1/60
➺ 1/f = 2+1 /60
➺ 1/f = 3/60
➺ 1/f = 1/20
➺ f = 20cm
Therefore, the focal length of the lens is 20 cm.
Now , we know that Power of lens is defined as the reciprocal of its focal length in metre.
• P = 1/f
Substitute the value we get
➺ P = 1/20/100
➺ P = 100/20
➺ P = 5 D
Therefore, the power of the lens is 5 Dioptre.