Chp 5 Unit A and B Flashcards
(28 cards)
Define lens
A lens is a transparent refracting medium bounded by either to spherical surfaces or one spherical surface and the other surface plane.
What is another name for convex lens?
Converging lens.
What is another name for concave lens?
Diverging lens.
Convex lens is - in the middle and - at the periphery.
Thick , thin.
Concave lens is - in the middle and - at the periphery
Thin, thick.
Convex lenses are of three types :
Bi convex
Plano convex
Concavo convex
Concave lenses are of three types:
Bi concave
Plano concave
Convexo concave.
Concavo convex is a —- lens and convexo concave is a —– lens.
Converging, diverging.
A convex lens has a — actions and concave lens has a —’ action on incident rays.
Converging, diverging.
Define centre of curvature.
The centre of the sphere whose part is the lens surface is called the centre of curvature of that surface of the lens.
Define radius of curvature.
The radius of the sphere whose part is the length surface is called the radius of curvature of that surface of the lens.
Define principle axis.
Principle axis is the line joining the centres of curvature of the two surfaces of the line.
Ray of light directed towards the optical centre of a thin lens can be considered to pass through the lens dash and dash.
Undeviated and undisplaced.
Define optical centre
Optical centre of a thin lens is the point on the principle access of a lens such that a Ray of light directly towards at passes un deviated through it
Define focal plane. Also first and second focal plane.
A plane normal to the principal Axis passing through the focus is called the focal plane.
Define focal length. Also first and second focal length.
The distance of focus from the optical centre of a lens is called its focal length. (Phrase the answer for first and second focal length)
If the medium on both sides of a lens is same its first and second focal lens are?
Equal
Convex lens has a dash focus while in a concave lens the focus is dash.
Real, virtual.
Differentiate between real and virtual image?
1) a real image is formed due to actual intersection of the rays reflected by the lens.
A virtual image is formed when the race refracted by the lens appear to meet if their produced backwards.
2) real image can be obtained on a screen.
A virtual image cannot be obtained on a screen.
3) real image is inverted with respect to the object.
A virtual image is erect with respect to the object.
If the position of object is at infinity in convex lens, the application will be?
In this manner a convex lens is used either as a burning glass or a camera lens. To use the convex lens as a burning glass the race of light from the sun are brought to focus on a piece of paper kept in the second focal plane of the lens due to sufficient heat of the sun rays the paper burns. In a camera the object lies very far from the lens and the image is formed at the camera film which is placed at the second focus of the lens.
When the position of object is beyond 2F1, what will be its application ?
A convex lens is used in this manner as a camera lens when the object, not very far, is to be photograph.
What will be the application for the lens when the object is between F1 and 2F1?
In this manner a convex lens is used in cinema and slide projectors.
What will be the application for the lens when the object is at F1?
In this manner a convex lens is used in the collimator of a spectrometer to obtain a parallel beam of light by placing the source of light at the focus of a convex lens.
What will be the application for the lens when the object is between the lens and focus that is between optical centre and focus?
In this manner a convex lens is used as a reading lens to form a magnified virtual image of a tiny object used in hypermetropia.
