Sign convention for plano concave lens ,convex concave lens
Asked by Harshit | 22nd Jan, 2017, 11:22: AM
Sign convention for reflection by Lens
In this convention, the pole (P) of the mirror is taken as the origin. The principal axis of the mirror is taken as the x-axis (X′X) of the coordinate system.The distances are measured from the optical centre.
The sign convention is as follows:
- The object is always placed to the left of the mirror. This implies that the light from the object falls on the mirror from the left-hand side.
- All distances parallel to the principal axis are measured from the pole of the mirror.
- All distances measured to the right of the origin (along +x-axis) are taken as positive, while those measured to the left of the origin (along −x-axis) are taken as negative.
- Distances measured perpendicular to and above the principal axis (along +y-axis) are taken as positive.
- Distances measured perpendicular to and below the principal axis (along −y-axis) are taken as negative.
- According to the sign convention, the focal length of a convex lens is positive and that of a concave lens is negative.
Note: The sign conventions for all types of lenses is the same. Infact the sign convention for spherical mirrors and lenses is also same (Except for the focal length).
Answered by Yashvanti Jain | 23rd Jan, 2017, 11:57: AM
- 35. A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its image on the screen. (A) In which direction does he move the lens to focus the flame on the screen? (B) What happens to the size of the image of the flame formed on the screen? (C) What difference is seen in the intensity (brightness) of the image of the flame on the screen? (D) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?
- How many types of image forms due to lenses ? What are those ? Mention the differences
- An object 50cm tall is placed on the principal axis of a convex lens.Its 20cm tall image
- How does the size of image change as the object is brought from closer to infinite towards the convex lens?
- The object 5cm high is placed in front of a lens of power +2D. Two times real and magnified image of the object is attained by the lens. Find 1)Object distance 2)Image distance 3)height of the image
- relation between intensity of image and aperture when half of the lens is covered
- An object is placed before a concave lens of focal length 12cm. The size of the image formed by the lens is half the size of the object. Calculate the distance.
- draw the ray diagram for getting a magnified inverted real image by using a convex lens
- why focal length of convex lens is taken as positive
- Which lens form virtual and erect image?
Kindly Sign up for a personalised experience
- Ask Study Doubts
- Sample Papers
- Past Year Papers
- Textbook Solutions
Verify mobile number
Enter the OTP sent to your number