Question 1 :
The relation between the linear magnification $m,$ the object distance $u$ and the focal length $f$ is
Question 2 :
Convex lens are used in eyeglasses to correct which type of defect?<br>
Question 4 :
The magnification of an image by a convex lens is positive only when the project is placed:
Question 5 :
Which one of the following materials cannot be used to make a lens?
Question 7 :
A concave lens forms the image of an object which is :<br><br>
Question 11 :
The lens of a simple magnifier has a focal length of 2.5 cm. Calculate the angular magnification produced when (a) the image is at least distance of distinct vision, and (b) infinity.
Question 12 :
The magnifications produced by a convex lens for two different of an object are $m_1$ and $m_2$ respectively $(m_1 >m_2)$. If 'd' is the distance of separation between the two positions of the object then the focal length of the lens is
Question 13 :
The sun subtends an angle of $(1/2)^o$ at earth.The image of the sun is obtained on a screen using a converging lens of focal length 1.5 cm.The diameter of the image will be :
Question 14 : <p>A convex lens produces an image of an object on a screen with a magnification of $\frac{1}{2}$ .When the lens is moved 30 cm away from the object, the magnification of the image is 2.The focal length of the lens is</p>
Question 15 :
For which of the following is $f > 0$:<br/><br/>I. Concave mirror<br/>II. Convex mirror<br/>III. Converging lens<br/>
Question 17 :
<span>A boy uses spectacles of focal length 60 cm. Name the defect of vision he is suffering from which lens is used for the correction of this defect? Compute the power of this lens</span>
Question 18 :
The flat face of a plano-convex lens of focal length $10$cm is silvered. A point source placed $30$cm in front of the curved surface will produce a.
Question 19 :
Find out the correct option from the following.<br>(a) The magnification is positive for all virtual images and is negative for all real images.<br>(b) The magnification of concave lens and convex mirror is always positive where as the magnification of convex lens and concave mirror can be positive or negative depending on the position of the object before the lens.<br>
Question 20 :
An object placed at a distance of <b>16 cm</b> from first principal focus of convex lens, produces a real image at a distance of <b>36 cm </b>from its second principal focus. Then the focal length of the lens is :
Question 22 : <span>In the table below, column I lists various mirrors and lenses and column II their uses, qualities or properties.</span><div><br/><table class="wysiwyg-table"><tbody><tr><td>column I</td><td>Column II</td></tr><tr><td>I. Plane mirror</td><td>A. Feels thinner in the middle.</td></tr><tr><td>II. Concave mirror</td><td>B. Always forms virtual image.</td></tr><tr><td>III. Convex mirror</td><td>C. Always forms virtual image of smaller size.</td></tr><tr><td>IV. Concave lens </td><td>D. Is used by dentists to examine teeth.</td></tr><tr><td>V. Convex lens</td><td>E. Can be used as reading glass.<br/></td></tr></tbody></table>The correct matching is:</div>
Question 23 :
An image of a bright square is obtained on a screen with the aid of a convergent lens. The distance between the square and the lens is $40\ cm$. The area of the image is nine times larger than that of the square. Select the correct statement(s).
Question 24 :
The final image in an astronomical telescope is _______ the original object . Fill in the gap.<br/>
Question 25 :
Image of an object at infinity is formed by a convex lens of focal length $30 \ cm$ such that the size of the image is $2 \ cm$. If a concave lens of focal length $20\ cm$ is placed in between the convex lens and the image, at a distance $26\ cm$ from the convex lens, size of the new image is:
Question 26 :
A point object is placed on the principal axis of the convex lens of focal length 20cm at a distance 40 cm to the left on it. The diameter of the lens is 10cm. If the eye is placed 60cm to the right of the lens at a distance h below the principal axis, then max value of 'h' to see the image is
Question 27 :
Three convex lenses are available having focal lengths of $4 cm, 40 cm$ and $4 m$ respectively. Which one could be used as magnifying glass?
