QUESTIONS: (5 marks each) Question 1. With the help of ray diagrams, show the formation of images of an object by a concave mirror. When it is placed (i)beyond the centre of curvature (ii)at the centre of curvature. Question 2. Draw ray diagrams to show the formation of image by an object by a concave lens when the object is placed (i)at infinity (ii)between infinity and optical centre of the lens. Question 3. Draw a labelled ray diagram to locate the image of an object formed by a convex lens of Focal length 20 cm when the object is placed 30 cm away from the lens. Question 4. What is meant by the power of a lens? What is its SI unit? Name the type of lens whose power is positive. The image of an object formed by a lens is real, inverted and of the same size as the object. If the image is at a distance of 40 cm from the lens, what is the nature and power of the lens? Draw ray diagram to justify your answer. Question 5. One half of a convex lens of focal length 10 cm is covered with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens? Draw a ray diagram to justify your answer. Question 6. With the help of a ray diagram, state and explain the laws of reflection of light at a plane mirror. Mark the angle of incidence and reflection clearly in the diagram. If the angle of incidence is 32.5o, what will be the angle of reflection? Question 7. It is desired to obtain an erect image of an object, using concave mirror of focal length of 12 cm. (i)What should be the range of distance of an object placed in front of the mirror? (ii)Will the image be smaller or larger than the object? Draw ray diagram to show the formation of image in this case,. (iii)Where will the image of this object be, if it is placed 6 cm in front of the mirror? Draw ray diagram for this situation to justify your answer. Show the position of pole, principal focus and the centre of curvature in the ray diagram. Question 8. A student has three concave mirrors A, B and C of focal lengths 20 cm, 15 cm and 10 cm respectively. For each concave mirror he performs the experiment of image formation for three values of object distance of 30 cm, 10 cm and 20 cm. Giving reason answer the following: (a)For the three object distances, identify the mirror which will form an image equal in size to that of object. Find at least one value of object distance. (b)Out of the three mirrors, identify the mirror which would be preferred to be used for shaving purpose. (c)For the mirror B, draw ray diagram for image formation for any two given values of object distance.
Answers
Answer:
At noon we know that the sun is overhead and when the sun is overhead , it has less air to travel through. We also know that scattering occurs due to dust and other suspended particles in air . So, scattering is reduced if the distance to be travelled in air is reduced.
Hope this helps !!
Ray diagrams are useful tools for visualizing the formation of images by mirrors. They allow us to trace the path of light rays from an object to a mirror and then to our eyes, so that we can determine the location, size, and type of image that is formed. Here's how you can use ray diagrams to show the formation of images by a concave mirror when the object is placed (i) beyond the center of curvature and (ii) at the center of curvature.
(i) Object Beyond the Center of Curvature:
Draw a vertical line to represent the axis of the mirror.
Draw the mirror as a curved line, labeled as a concave mirror.
Place the object beyond the center of curvature, to the right of the mirror's axis.
Draw three rays of light originating from the top, center, and bottom of the object, and extend them to the mirror.
At the mirror, the rays of light are reflected according to the laws of reflection. Draw the reflected rays so that they converge at a point to the left of the mirror's axis.
This point is the location of the image, which is virtual, erect, and smaller than the object.
(ii) Object at the Center of Curvature:
Draw a vertical line to represent the axis of the mirror.
Draw the mirror as a curved line, labeled as a concave mirror.
Place the object at the center of curvature, on the right side of the mirror's axis.
Draw two rays of light originating from the top and bottom of the object, and extend them to the mirror.
At the mirror, the rays of light are reflected according to the laws of reflection. Draw the reflected rays so that they are parallel to the mirror's axis.
These rays will never converge, so there is no image formed.
Note: In both cases, the size of the image can be determined by drawing additional rays and analyzing their intersection with the mirror's axis.
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