NEET Exam  >  NEET Questions  >  A telescope has an objective lens of focal le... Start Learning for Free
A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :
  • a)
    30°
  • b)
    15°
  • c)
    60°
  • d)
Correct answer is option 'C'. Can you explain this answer?
Most Upvoted Answer
A telescope has an objective lens of focal length 150 cm and an eyepie...
To find the angle formed by the image of the tower, we can use the formula for angular magnification:

\(M = -\frac{f_o}{f_e}\)

Where:
\(M\) is the angular magnification
\(f_o\) is the focal length of the objective lens
\(f_e\) is the focal length of the eyepiece

Substituting the given values into the formula:

\(M = -\frac{150}{5} = -30\)

Now, to find the angle formed by the image of the tower, we can use the formula for angular size:

\(\theta = \frac{h}{d}\)

Where:
\(\theta\) is the angle formed by the image
\(h\) is the height of the tower
\(d\) is the distance from the tower to the observer

Substituting the given values into the formula:

\(\theta = \frac{50}{1000} = 0.05\)

Since the formula for angular magnification is negative, the image formed by the telescope is inverted. Therefore, the angle formed by the image of the tower is -0.05 radians.
Free Test
Community Answer
A telescope has an objective lens of focal length 150 cm and an eyepie...
The tower PQ in figure (19.5) subtends an angle α on the objective. As uo​ is very large, the first image P Q' is formed in the focal plane of the objective.
tanα = α = P′Q′/f∘​ ..(i)
 
The final image P"Q" subtends an angle β  on the eyepiece (and hence on the eye). We have from the triangle P Q'E:
tanβ = β = ′P′Q′/EP​ ...(ii)
 
The telescope is set for normal adjustment so that the final image is formed at infinity, the first image P'Q' must be in the focal plane of the eyepiece.Then EP=fe​ .
Thus, equation (ii) becomes
tanβ=β=f∘/fe​​​ ...(iii)
dividing equation (iii) by (i)
β/α​=​f∘/fe​​...(iv)
 
from equation (i) The α=P′Q′/f∘​
P′Q′=mh1​ ...(v) where m is magnification of objective lens m=uv​ 
where v is position of first image P'Q' and u is position of tower v=f∘=150cm,u=1000m substituting value of m in equation (v) m
 
P′Q′= 0.15/1000 x ​50m=.0075m
α= 0.0075/0.15 ​= 0.05
 
value of β can be obtained from equation (v)
 
tanβ=.05.15​×α=30×.05=1.5rad
β=56.3 which is closer to 60°

Fig 19.5
Attention NEET Students!
To make sure you are not studying endlessly, EduRev has designed NEET study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in NEET.
Explore Courses for NEET exam

Top Courses for NEET

A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer?
Question Description
A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer?.
Solutions for A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for NEET. Download more important topics, notes, lectures and mock test series for NEET Exam by signing up for free.
Here you can find the meaning of A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer?, a detailed solution for A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer? has been provided alongside types of A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is θ, then θ is close to :a)30°b)15°c)60°d)1°Correct answer is option 'C'. Can you explain this answer? tests, examples and also practice NEET tests.
Explore Courses for NEET exam

Top Courses for NEET

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev