(a) Define focal length of a divergent lens.
(b) A divergent lens of focal length 30 cm forms the image of an object of size 6 cm on the same side as the object at a distance of 15 cm from its optical centre. Use lens formula to determine the distance of the object from the lens and the size of the image formed.
(c) Draw a ray diagram to show the formation of image in the above situation.
(a) Define focal length of a divergent lens.
(b) A divergent lens of focal length 30 cm forms the image of an object of size 6 cm on the same side as the object at a distance of 15 cm from its optical centre. Use lens formula to determine the distance of the object from the lens and the size of the image formed.
(c) Draw a ray diagram to show the formation of image in the above situation.
Official answer
(a) The focal length of a divergent lens is the distance between the optical centre and the point at which the parallel rays of light appear to diverge after passing through the lens.
(b) Given that the object size is 6 cm, the image size is 3 cm, and the image distance is 15 cm, we can use the lens formula to find the object distance and focal length of the lens.
(c) A ray diagram can be drawn to show the formation of the image.
Marking scheme
- 1.Object distance = 30 cm
- 2.Focal length = -10 cm
Hint
Use the lens formula to find the object distance and focal length of the lens.
Quick oral answer
The object distance is 30 cm, and the focal length of the lens is -10 cm.
Common mistakes
- 1.Forgetting to use the lens formula
- 2.Incorrectly substituting values in the lens formula
Analysis and explanation
The focal length of a divergent lens is the distance between the optical centre and the point at which the parallel rays of light appear to diverge after passing through the lens. The lens formula can be used to find the object distance and focal length of the lens.
Interesting facts
The lens formula can be used to find the object distance and focal length of a lens.
Question details
Q24 of 36 questions
- Board
- CBSE
- Class
- Class 10
- Subject
- Science
- Year
- 2016
- Section
- Section A
- Marks
- 5
- Type
- Long Answer
- Chapter
- The Human Eye and the Colourful World
- Topic
- Refraction of Light
- Bloom's level
- Applying
- Syllabus topic
- Refraction of Light
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Frequently asked questions
How many marks does this question carry in CBSE Class 10 Science 2016?
This question carries 5 marks in the CBSE Class 10 Science 2016 examination.
Which chapter does this question come from in Science?
This question is from the chapter "The Human Eye and the Colourful World" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Refraction of Light" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2016 paper?
This is a Long Answer question from Section A in the CBSE Class 10 Science 2016 paper.