Q1. If an object of 7cm height is placed at a distance of 12 cm from a convex lens of focal length 8cm, find the position, nature and height of the image.
Q2. A convex lens of focal length 10cm is placed at a distance of 12 cm from a wall. How far from the lens should an object be placed so that as to form its real image on the wall.
Q3. A diverging lens of focal length 15 cm forms an image 10 cm from the lens. Draw a scale diagram and prove that object is placed 30 cm away from the lens. Use a scale of 1:5. Also find the magnification of the image.
Q4. A lens has a power of -2.5 D. What kind of lens it is and what is its focal length?
Q5. An object of height 4 cm is placed at a distance of 15 cm in front of a concave lens of power -10 D. Find the size of the image.
Q6. Find the position and nature of image of an object 5 cm high and 10 cm in front of a convex lens of focal length 6 cm.
Q7. An object 2 cm high is placed at a distance of 10 cm from a convex lens of focal length 20 cm. Find the position , nature and size of the image.
Q8. An object which is placed 10 cm in front of a lens produces a real image three times magnified. Where is the image formed? What is the focal length of the lens.
Q9. A diverging lens has a focal length 3 cm. Calculate its power and give the units of power.
Q10. Two lenses one of focal length 20 cm ( convex lens) and another of focal length - 15 cm (concave) lens are placed in contact. What is the focal length and power of combination
Q11. An object placed at a distance of 50 cm from a lens produces a virtual image at a distance of 10 cm in front of the lens. Draw a diagram to show the formation of image and calculate the focal length.
Saturday, June 20, 2009
Tuesday, June 9, 2009
ASSIGNMENT 1- LIGHT - CBSE X
Q1. What is focal length of plane mirror ?
Q2. How does the frequency of a beam of ultra violet light change when it goes from air to glass?
Q3. A concave mirror is placed in water will there be any change in focal length? Give reason.
Q4. When light under goes refraction, what happens to its frequency and wavelength?
Q5. Differentiate between real and virtual image. ( 3 differences)
Q6. What is the value of refractive index of air?
Q7. Define power of a lens ? What is its unit? Define it.
Q8. What is the cause for refraction of light?
Q9. The refractive index of water is 4/3 and for glass it is 3/2, with respect to air. What is the refractive index of glass w.r.t. water?
Q10. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where is the object placed ?
Q11. Where should an object be placed, so that a real inverted image of same size is obtained by convex lens?
Q12. when we focus sunlight using a convex lens at the tip of a match stick, what will happen? Why?
Q13. How is power related to focal length?
Q14. A convex mirror and a convex lens are held separately in water. What changes if any, do you expect in the focal length of either?
Q15. Whatever may be the position of object, the image appears to be erect. Give nature of mirror with reason.
Q16. Define refractive index.
Q17. Magnification by a spherical mirror is m= +0.5. What does it mean?
Q18. Prove that n21 = 1/n12
Q19. What is the meaning of optical centre and principal focus.
Q20. How does the light ray bend when it travels from
(i) a denser to a rarer medium
(ii) a rarer to denser medium
Q21. An object of size 'l' cm is placed in front of a
(i) convex mirror
(ii) concave mirror.
With a neat ray diagram explain how an erect image is formed.
Q22. What is lateral displacement? What are the factors that affect the same?
Q2. How does the frequency of a beam of ultra violet light change when it goes from air to glass?
Q3. A concave mirror is placed in water will there be any change in focal length? Give reason.
Q4. When light under goes refraction, what happens to its frequency and wavelength?
Q5. Differentiate between real and virtual image. ( 3 differences)
Q6. What is the value of refractive index of air?
Q7. Define power of a lens ? What is its unit? Define it.
Q8. What is the cause for refraction of light?
Q9. The refractive index of water is 4/3 and for glass it is 3/2, with respect to air. What is the refractive index of glass w.r.t. water?
Q10. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where is the object placed ?
Q11. Where should an object be placed, so that a real inverted image of same size is obtained by convex lens?
Q12. when we focus sunlight using a convex lens at the tip of a match stick, what will happen? Why?
Q13. How is power related to focal length?
Q14. A convex mirror and a convex lens are held separately in water. What changes if any, do you expect in the focal length of either?
Q15. Whatever may be the position of object, the image appears to be erect. Give nature of mirror with reason.
Q16. Define refractive index.
Q17. Magnification by a spherical mirror is m= +0.5. What does it mean?
Q18. Prove that n21 = 1/n12
Q19. What is the meaning of optical centre and principal focus.
Q20. How does the light ray bend when it travels from
(i) a denser to a rarer medium
(ii) a rarer to denser medium
Q21. An object of size 'l' cm is placed in front of a
(i) convex mirror
(ii) concave mirror.
With a neat ray diagram explain how an erect image is formed.
Q22. What is lateral displacement? What are the factors that affect the same?
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