Question 1 :
The maximum magnification that can be obtained with a convex lens of focal length $2.5\ cm$ is ( the least distance of distinct vision is $25\ cm$)
Question 2 :
In order to get a diminished virtual image, the object can be placed anywhere in front of a :
Question 3 :
State whether true or falseA convex mirror is used for obtaining a real and magnified image.
Question 4 :
Under which of the following conditions will a convex mirror of focal length <i>f</i> produces an image ofreal object that is erect, diminished and virtual
Question 5 :
A photograph of a horse is taken by a camera whose lens has been painted with black stripes. The photograph will be of a :
Question 6 :
A parallel beam of white light is incident normally on a water film $1.0 \times 10^{-4}$ cm thick. Find the wavelength in the visible range $(400\ nm-700\ nm)$ which are strongly transmitted by the film. Refractive index of water $= 1.33$.
Question 7 :
The time from sunrise to sunset is lengthened by about 4 minutes on the earth because
Question 8 :
The near point and far point of a person are $40$ cm and $250$ cm respectively. Determine the power of the lens he/she should use while reading a book kept at distance $25$cm from the eye.
Question 9 :
Assertion: Magnification of a convex mirror is always positive, but that of a concave mirror may be both positive or negative.
Reason: It depends on the sign convention chosen.
Question 10 :
A convex lens of focal length $84\ cm$ is in contact with a concave lens of focal length $12\ cm$. The power of combination (in diopters) is
Question 11 :
Two thin lenses of power $+3.5D, -2D$ are placed in contact. Find the power of lens combination.
Question 12 :
An object is placed at $30$ cm distance from a concave mirror of focal length $20$ cm, then nature, magnification of the image will be:
Question 13 :
A $4.5 cm$ needle is placed $12 cm$ away from a convex mirror of focal length $15 cm$. Find the location of the image and the magnification.
Question 14 :
The image obtained while finding the focal length of convex lens is...................
Question 15 :
A water film is formed on a glass-block. A light ray is incident on water film from air at an angle of$\displaystyle { 60 }^{ \circ }$ with the normal. The angle of incidence on glass slab is<br>($\displaystyle { \mu }_{ g } = 1.5,{ \mu }_{ w } = \frac { 4 }{ 3 }$)
Question 16 :
Air has refractive index $1.0003$. Find the thickness of air column which will contain one more wavelength of yellow light of $6000$ $A^0$ than in same thickness of vacuum.
Question 17 :
A short linear object of length $b$ lies along the axis of a concave mirror of focal length $f$ at a distance $u$ from the pole of the mirror. The size of the image is approximately equal to:<br/>
Question 18 :
The glancing angle of incidence is $10^{\circ}$. What will be the glancing angle of reflection?
Question 19 :
A $2.5$ dioptre lens forms a virtual image which is $4$ times the object placed perpendicularly on the lens. Then the required distance of the object from the lens is .
Question 20 :
The distance between an object and its doubly magnified image by a concave mirror is: [ Assume $f$ = focal length]
