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Optics
A screen is placed 90 cm from an object. When a converging lens is moved between the screen and the object , at two different positions images can be produced on the screen. If the distance between the positions of the lens is 20 cm , find the focal length of the lens
Optics
When an object is moving along the principal axis of a lens at object distances 8 cm and 16 cm , the images being thrice the size of the object can be found. Find the type and focal length of the lens
Optics
12. An object ‘o’ , a converging lens L of focal length 15 cm where object distance is 30 cm and concave mirror M are placed. the distance between o and mirror is 50 cm. If the object and the final image coincide , the focal length of M is ( 1 ) 10 cm ( 2 ) 15 cm ( 3 ) 20 cm ( 4 ) 25 cm ( 5 ) 30 cm
Optics
14. A bulb ‘o’ is placed 12 cm below the water surface. A converging lens of focal length 10 cm is placed 1 cm above the water surface. If the refractive index of water is 4/3 , the final image of ‘o’ is formed at
( 1 ) 9 cm above the lens. ( 2 ) 13 cm above the lens. ( 3 ) 20 cm above the lens. ( 4 ) 25 cm above the lens. ( 5 ) infinity.
( 1 ) 9 cm above the lens. ( 2 ) 13 cm above the lens. ( 3 ) 20 cm above the lens. ( 4 ) 25 cm above the lens. ( 5 ) infinity.
Optics
Number of images formed by a pair of plane mirrors is given by n = 360/Ø, n-1 if n is even and n (asymmetrical) of n-1 (symmetrical).
What will be the number of images formed if n is a fraction example n = 360/225??
What will be the number of images formed if n is a fraction example n = 360/225??
Optics
A convex (converging) lens can be used to light a fire (if you are stranded on a desert island,
for example). Consider a lens with focal length 0.200 m. How far away must a piece of
paper be held to set in on fire most effectively? Give a reason for your answer.
for example). Consider a lens with focal length 0.200 m. How far away must a piece of
paper be held to set in on fire most effectively? Give a reason for your answer.
Optics
Consider the lens equation (1) for a convex (converging) lens. If you were to determine
where an image is formed for an object very, very far away, like the sun, an approximate
relationship between the image length and the focal point can be derived. By looking up the
distance from the earth to the sun to assist you, derive this relationship. Remember to
reference properly!
where an image is formed for an object very, very far away, like the sun, an approximate
relationship between the image length and the focal point can be derived. By looking up the
distance from the earth to the sun to assist you, derive this relationship. Remember to
reference properly!
Optics
Consider an object which is 0.700 m high, placed 2.00 m in front of a convex (converging) lens with focal point 0.500 m. Draw a scale diagram of the object and the lens. Clearly indicate at least two rays from the object that strike the lens. Make sure you indicate your chosen scale in the drawing. Include a picture of your drawing! Determine the image length and image height, and describe the image formed. DO NOT use the lens equations.
Optics
An object is moved from a distance of 30 cm to a distance of 10 cm in front of a converging lens of focal length 20 cm. What happens to the image?
(a) The image goes from real and upright to real and inverted.
(b) The image goes from virtual and upright to real and inverted.
(c) The image goes from virtual and inverted to real and upright.
(d) The image goes from real and inverted to virtual and upright.
(e) None are correct.
(a) The image goes from real and upright to real and inverted.
(b) The image goes from virtual and upright to real and inverted.
(c) The image goes from virtual and inverted to real and upright.
(d) The image goes from real and inverted to virtual and upright.
(e) None are correct.
Optics
3. The photo detector output in a cutback attenuation set up is 3.5V at the far end of the fiber. After cutting the fiber 2m at the near end, 5km from the far end, photo detector output read was 4.2 V. What is the attenuation of fiber in dB/km?
