Advertisements
Advertisements
प्रश्न
How will you determine the focal length of a convex lens by the plane mirror method?
उत्तर
Set-up the apparatus as shown in the figure. M is a rectangular sheet of plane mirror fixed in a vertical position in a stand and convex lens L is mounted on a lens stand. P is a pin, set up vertically in a pin stand. Mirror M is placed at the back of the lens. Now the pin P is adjusted by moving it backward and forward so that a real and inverted image of the pin is formed after reflection from the plane mirror M. The position of the pin is carefully adjusted so that there is no parallax between the upper tip of the pin and its inverted image. The distance between the needle and the lens gives the focal length of the lens. In this position rays of light starting from the tip of the pingo parallel to the principal axis and strike the reflecting surface of the mirror M normally. The parallel beam of light is reflected back along the same path and forms the image P‘ of the tip P at the focus of the lens.
APPEARS IN
संबंधित प्रश्न
Describe with the help of a ray-diagram, the size, nature and position of the image formed by a convex lens when an object is placed beyond 2f in front of the lens.
You eye contains a convex lens. Why is it unwise to look at the sun?
A student did an experiment with a convex lens. He put an object at different distances 25 cm, 30 cm, 40 cm, 60 cm and 120 cm from the lens. In each case he measured the distance of the image from the lens. His results were 100 cm, 24 cm, 60 cm, 30 cm and 40 cm, respectively. Unfortunately his results are written in wrong order.
What would be the image distance if the object distance was 90 cm?
A beam of parallel light rays is incident through the holes on one side of a box and emerges out through the holes on its opposite side as shown in the diagram below:
Which of the following could be inside the box?
(a) a rectangular glass block
(b) a concave lens
(c) a convex lens
(d) a glass prism
The diagrams (a) and (b) in Figure below show the refraction of a monochromatic ray of light through a parallel sided glass block and a prism respectively. In each diagram, label the incident, refracted emergent rays and the angle of deviation.
Where is the image formed?
A student focussed the image of a distant object using a device ‘X’ on a white screen ‘S’ as shown in the figure. If the distance of the screen from the device is 40 cm, select the correct statement about the device.
(A) The device X is a convex lens of focal length 20 cm.
(B) The device X is a concave mirror of focal length 40 cm.
(C) The device X is a convex mirror of radius of curvature 40 cm.
(D) The device X is a convex lens of focal length 40 cm.
Which lens can produce a real and inverted image of an object?
A beam of light is incident through the holes on side A and emerges out of the holes on the other face of the box as show in the figure. Which of the following could be inside the box?
Distinguish between:
Concave lens and Convex Lens
