2. A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? -Physics-10

2. A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? -Physics-10
by

1 Answer

Answer :

The position of the image should be at 2F since the image is the real and same size. It is given that the image of the needle is formed at a distance of 50 cm from the convex lens. Therefore, the needle is placed in front of the lens at a distance of 50 cm. Object distance (u) = – 50 cm Image distance, (v) = 50 cm Focal length = f According to the lens formula,
by

Related questions

3. Where should an object be placed in front of a convex lens to get a real image of the size of the object? -Physics-10

Description : 3. Where should an object be placed in front of a convex lens to get a real image of the size of the object? -Physics-10

Last Answer : (b) The object should be placed at twice the focal length

14. An object 5 cm is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position, nature and size of the image. -Physics-10

Description : 14. An object 5 cm is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position, nature and size of the image. -Physics-10

Last Answer : Object distance (u) = - 20 cm Object height (h) = 5 cm Radius of curvature (R) = 30 cm Radius of curvature = 2 Focal length R = 2f f = 15 cm According to the mirror formula, ... image height indicates that the image formed is erect. Hence, the image formed is erect, virtual, and smaller in size.

A convex lens has a focal length of 10 cm. At what distance from the lens should the object be placed so that it forms a real and inverted image 20 cm away from the lens? What would be the size of the image formed if the object is 2 cm high? With the help of a ray diagram show the formation of the image by the lens in this case. -Physics

Description : A convex lens has a focal length of 10 cm. At what distance from the lens should the object be placed so that it forms a real and inverted image 20 cm away from the lens? What would be the size of ... ? With the help of a ray diagram show the formation of the image by the lens in this case. -Physics

Last Answer : This is the Answe:

15. An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed so that a sharply focused image can be obtained? Find the size and nature of the image. -Physics-10

Description : 15. An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed so that a sharply focused image can be obtained? Find the size and nature of the image. -Physics-10

Last Answer : Object distance (u) = – 27 cm Object height (h) = 7 cm Focal length (f) = – 18 cm According to the mirror formula, The negative value of image height indicates that the image formed is inverted.

12. An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image. -Physics-10

Description : 12. An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image. -Physics-10

Last Answer : Focal length of convex mirror (f) = +15 cm Object distance (u) = - 10 cm According to the mirror formula, The image is located at a distance of 6 cm from the mirror on the other ... and a value of less than 1 of magnification indicates that the image formed is virtual and erect and diminished.

11. A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram. -Physics-10

Description : 11. A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram. -Physics-10

Last Answer : Focal length of concave lens (OF1), f = – 15 cm Image distance, v= – 10 cm According to the lens formula, The negative value of u indicates that the object is placed 30 cm in front of the lens. This is shown in the following ray diagram.

2. A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located? -Physics-10

Description : 2. A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located? -Physics-10

Last Answer : Magnification produced by a spherical mirror: Object distance (u) = – 10 cm v = 3 × (- 10) = – 30 cm Therefore, the negative sign indicates that an inverted image is formed in front of the given concave mirror at a distance of 30 cm.

9. One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations. -Physics-10

Description : 9. One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations. -Physics-10

Last Answer : Yes, it will produce a complete image of the object, as shown in the figure. This can be verified experimentally by observing the image of a distant object like a tree on a screen when the ... the lens is covered with a black paper. However, the intensity or brightness of the image will reduce.

10. An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed. -Physics-10

Description : 10. An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed. -Physics-10

Last Answer : Height of the Object, h0 = 5 cm Distance of the object from converging lens, u = -25 cm Focal length of a converging lens, f = 10 cm Using lens formula, Thus, the image is inverted and formed at a distance of 16.7 cm behind the lens and measures 3.3 cm. The ray diagram is shown below.

An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. -Physics

Description : An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. -Physics

Last Answer : The focal length' of convex length is 7.14 cm. Solution: The given quantities are Height of the object h = 50 cm Height of the image formed h' = -20 cm Image distance v = 10 cm The image ... object distance will be So the focal length will be Thus the focal length of the convex lens is 7.14 cm

An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object is formed on the screen. What is the focal length of the convex lens and size of the image formed on the screen? Draw a ray diagram to show the formation of the image in this position of the object with respect to the lens. -Physics

Description : An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object ... diagram to show the formation of the image in this position of the object with respect to the lens. -Physics

Last Answer : Since, object-screen distance is double of object-lens separation, the object is at a distance of 2f from the lens and the image should be of the same size of the object.

We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? -Physics-10

Description : We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? -Physics-10

Last Answer : Range of the distance of the object = 0 to 15 cm from the pole of the mirror. Nature of the image = virtual, erect, and larger than the object.

A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. -Physics

Description : A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. -Physics

Last Answer : Answer. I hope it helped you.

2. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. [All India] -Chemistry-10

Description : 2. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens. [All India] -Chemistry-10

Last Answer : this is the answer for the respected question

Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed: (i) at the centre of curvature of a concave mirror (ii) between the pole P and focus F of a concave mirror (iii) in front of a convex mirror (iv) at 2F of a convex lens (v) in front of a concave lens -Physics

Description : Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed: (i) at the centre of curvature of a concave mirror (ii) between the pole P and focus F of ... front of a convex mirror (iv) at 2F of a convex lens (v) in front of a concave lens -Physics

Last Answer : Answer. Nature of image: Real, inverted and same size image is formed at the centre of curvature. Nature of image: Virtual, enlarged and erect image is formed behind the mirror. Nature of image: Virtual ... : Virtual, erect and diminished image is formed between O and F on the same side of object.

A convex lens is placed on an optical bench and is moved till it gives a real image of an object at a minimum distance of 80 cm from the latter. Find

Description : A convex lens is placed on an optical bench and is moved till it gives a real image of an object at a minimum distance of 80 cm from the latter. Find

Last Answer : A convex lens is placed on an optical bench and is moved till it gives a real image of an object ... cm from the lens, find the position of the image.

1. Find the focal length of a convex mirror whose radius of curvature is 32 cm. -Physics-10

Description : 1. Find the focal length of a convex mirror whose radius of curvature is 32 cm. -Physics-10

Last Answer : Radius of curvature (R) = 32 cm Radius of curvature = 2 × Focal length (f) R= 2f f = R/2 = 32/2 = 16 Therefore, the focal length of the given convex mirror is 16 cm.

At what distance should an object be placed from a convex lens of focal langth `15 cm` to obtain an image three times the size of the object ?

Description : At what distance should an object be placed from a convex lens of focal langth `15 cm` to obtain an image three times the size of the object ?

Last Answer : At what distance should an object be placed from a convex lens of focal langth `15 cm` to obtain an image three times the size of the object ?

A what distance must an object be placed from convex lens of power 4D to obtain a real image three times the size of the object ?

Description : A what distance must an object be placed from convex lens of power 4D to obtain a real image three times the size of the object ?

Last Answer : A what distance must an object be placed from convex lens of power 4D to obtain a real image three times the size of the object ?

In case of convex lens when the image formed is real, inverted and same size as the object then the object should have been at ______ position of lens. a) infinity b)focus c)2F d)between F and 2F

Description : In case of convex lens when the image formed is real, inverted and same size as the object then the object should have been at ______ position of lens. a) infinity b)focus c)2F d)between F and 2F

Last Answer : c)2F

4. A spherical mirror and a thin spherical lens have a focal length of -15 cm. The mirror and the lens are likely to be -Physics-10

Description : 4. A spherical mirror and a thin spherical lens have a focal length of -15 cm. The mirror and the lens are likely to be -Physics-10

Last Answer : (a) Both are likely to be concave.

15. An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object is formed on the screen. What is the focal length of the conve -Chemistry-10

Description : 15. An object 2 cm high is placed at a distance of 64 cm from a white screen. On placing a convex lens at a distance of 32 cm from the object it is found that a distinct image of the object is formed on the screen. What is the focal length of the conve -Chemistry-10

Last Answer : Since, object-screen distance is double of object-lens separation, the object is at a distance of 2f from the lens and the image should be of the same size of the object.

An object is placed on the principal axis of a convex lens of focal length 10 cm. If the distance of the object from the lens is 30 cm, what is the distance of the image formed? (1) 20 cm (2) 15 cm (3) 30 cm (4) 10 cm

Description : An object is placed on the principal axis of a convex lens of focal length 10 cm. If the distance of the object from the lens is 30 cm, what is the distance of the image formed? (1) 20 cm (2) 15 cm (3) 30 cm (4) 10 cm

Last Answer : (2) 15 cm

1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi] -Chemistry-10

Description : 1. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image formed. [Delhi] -Chemistry-10

Last Answer : Answer. hope this helps youu

A needle 10 cm long is placed along the axis of a convex lens of focal length 10 cm such that the middle point of the neddle is at a distance of 10 cm

Description : A needle 10 cm long is placed along the axis of a convex lens of focal length 10 cm such that the middle point of the neddle is at a distance of 10 cm

Last Answer : A needle 10 cm long is placed along the axis of a convex lens of focal length 10 cm such that ... lens. Find the length of the image of the neddle.

2. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object? -Physics-10

Description : 2. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object? -Physics-10

Last Answer : (d) The position of the object should be between the pole of the mirror and its principal focus.

3. Name the mirror that can give an erect and enlarged image of an object. -Physics-10

Description : 3. Name the mirror that can give an erect and enlarged image of an object. -Physics-10

Last Answer : The mirror that can give an erect and enlarged image of an object is Concave Mirror.

A sphere of 1 cm radius is placed at the distance of 50 cm from the convex lens of 10 cn focal length. What would be the height of the image of sphere ?

Description : A sphere of 1 cm radius is placed at the distance of 50 cm from the convex lens of 10 cn focal length. What would be the height of the image of sphere ?

Last Answer : 0.5cm

1. Why does a compass needle get deflected when brought near a bar magnet? -Physics-10

Description : 1. Why does a compass needle get deflected when brought near a bar magnet? -Physics-10

Last Answer : The compass needle is a small magnet. When the compass needle is brought close to a bar magnet, the magnetic field lines of the compass needle interact with the magnetic field lines of bar magnet, which causes the compass needle to deflect.

Find the focal length and power of a convex lens, which when placed in contact with a concave lens of focal length `25 cm` forms a real image `5` time

Description : Find the focal length and power of a convex lens, which when placed in contact with a concave lens of focal length `25 cm` forms a real image `5` time

Last Answer : Find the focal length and power of a convex lens, which when placed in contact with a concave ... the object placed `20 cm` from the combination.

4. Why do we prefer a convex mirror as a rear-view mirror in vehicles? -Physics-10

Description : 4. Why do we prefer a convex mirror as a rear-view mirror in vehicles? -Physics-10

Last Answer : Convex mirror is preferred as a rear-view mirror in cars and vehicles as it gives a wider field of view, which helps the driver to see most of the traffic behind him. Convex mirrors always form an erect, virtual, and diminished image of the objects placed in front of it.

17. A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging? -Physics-10

Description : 17. A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging? -Physics-10

Last Answer : Power of lens (P) = 1/f P = 1.5D f = 1/1.5 = 10/15 = 0.66 m A convex lens has a positive focal length. Therefore, it is a convex lens or a converging lens.

16. Find the focal length of a lens of power -2.0 D. What type of lens is this? -Physics-10

Description : 16. Find the focal length of a lens of power -2.0 D. What type of lens is this? -Physics-10

Last Answer : Power of lens (P) = 1/f P = -2D f = -1/2 = -0.5 m A concave lens has a negative focal length. Therefore, it is a concave lens.

1. Which one of the following materials cannot be used to make a lens? -Physics-10

Description : 1. Which one of the following materials cannot be used to make a lens? -Physics-10

Last Answer : (d) Clay cannot be used to make a lens because if the lens is made up of clay the light rays cannot pass through it

3. Find the power of a concave lens of focal length 2 m. -Physics-10

Description : 3. Find the power of a concave lens of focal length 2 m. -Physics-10

Last Answer : Focal length of concave lens (f) = 2 m Power of lens (P) = 1/f = 1/ (-2) = -0.5D

1. Define 1 dioptre of power of a lens. -Physics-10

Description : 1. Define 1 dioptre of power of a lens. -Physics-10

Last Answer : Dioptre is the SI unit of power of lens is denoted by the letter D. 1 dioptre can be defined as the power of a lens of focal length 1 metre.

An object is placed beyond 2F, in front of a convex lens, image will be formed : (a) between F and 2F (b) at focus (c) at the centre of curvature (d) between focus and Optical centre

Description : An object is placed beyond 2F, in front of a convex lens, image will be formed : (a) between F and 2F (b) at focus (c) at the centre of curvature (d) between focus and Optical centre

Last Answer : (a) between F and 2F

When object is placed _______ in front of convex lens than image formed is virtual, erect, magnified and on same side beyond F . a) between optical centre and F b)At F c)between F and 2F d)2F

Description : When object is placed _______ in front of convex lens than image formed is virtual, erect, magnified and on same side beyond F . a) between optical centre and F b)At F c)between F and 2F d)2F

Last Answer : a) between optical centre and F

If a real object is placed just inside the focal point of a diverging lens, the image is (a) Virtual, erect and diminished (b) Real, inverted and enlarged (c) Real, inverted and diminished (d) Virtual, erect and enlarged

Description : If a real object is placed just inside the focal point of a diverging lens, the image is (a) Virtual, erect and diminished (b) Real, inverted and enlarged (c) Real, inverted and diminished (d) Virtual, erect and enlarged

Last Answer : Ans:(a)

A concave lens can form a real and inverted image, when : (a) Object is placed at 2f (b) Object is placed beyond 2f (c) Object is placed between f and 2f (d) It can never form a real and

Description : A concave lens can form a real and inverted image, when : (a) Object is placed at 2f (b) Object is placed beyond 2f (c) Object is placed between f and 2f (d) It can never form a real and

Last Answer : (d) It can never form a real and inverted image.

9. When is the force experienced by a current–carrying conductor placed in a magnetic field largest? -Physics-10

Description : 9. When is the force experienced by a current–carrying conductor placed in a magnetic field largest? -Physics-10

Last Answer : When the direction of the current is perpendicular to the direction of the magnetic field is when the force experienced is the largest.

A concave mirror of focal length 15 cm can form a magnified, erect as well as inverted image of an object placed in front of it." Justify this statement stating the position of the object with respect to the pole of the mirror in both the cases for obtaining the images. -Science

Description : A concave mirror of focal length 15 cm can form a magnified, erect as well as inverted image of an object placed in front of it." Justify this statement stating the position of the object with respect to the pole of the mirror in both the cases for obtaining the images. -Science

Last Answer : For magnified and erect image the object is placed between pole P and focus F. For magnified and inverted image the object is placed either at focus or anywhere between F and C.

12. Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed: -Chemistry-10

Description : 12. Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed: -Chemistry-10

Last Answer : Answer. hope this helps you

5. No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be -Physics-10

Description : 5. No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be -Physics-10

Last Answer : (d) The mirrors are likely to be either plane or convex

A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its image on the screen. (a) In which direction does he move the lens to focus the flame on the screen? (b) What happens to the size of the image of the flame formed on the screen? (c) What difference is seen in the intensity (brightness) of the image of the flame on the screen? (d) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?

Description : A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its ... d) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?

Last Answer : (a) The student moves the lens away from the screen to focus the image because on moving the candle towards the lens, the image distance increases. (b)The size of the image increases when the object ... on the screen. A virtual image is formed behind the candle on the same side of the screen.

A small hole in the window of a closed room forms an inverted image of outside building on the opposite wall of the room. This happens because (a) the rays of light suffer lateral inversion on entering the hole (b) of the rectilinear propagation of light (c) the hole acts as a convex lens (d) the hole acts as a prism

Description : A small hole in the window of a closed room forms an inverted image of outside building on the opposite wall of the room. This happens because (a) the rays of light suffer lateral inversion on entering the ... propagation of light (c) the hole acts as a convex lens (d) the hole acts as a prism

Last Answer : Ans:(b)

14. An object 2 cm in size is placed 30 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? What will be the nature and the size of the -Chemistry-10

Description : 14. An object 2 cm in size is placed 30 cm in front of a concave mirror of focal length 15 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? What will be the nature and the size of the -Chemistry-10

Last Answer : Answer. hope this helps you

2. The radius of curvature of a spherical mirror is 20 cm. What is its focal length? -Physics-10

Description : 2. The radius of curvature of a spherical mirror is 20 cm. What is its focal length? -Physics-10

Last Answer : Radius of curvature (R) = 20 cm Radius of curvature of the spherical mirror = 2 × Focal length (f) R = 2f f= R/2 = 20 / 2 = 10 Therefore, the focal length of the spherical mirror is 10 cm.

A source of light and a screen are placed 90 cm apart. Where should a convex lens of 20 cm focal length be placed in order to form a real image of the

Description : A source of light and a screen are placed 90 cm apart. Where should a convex lens of 20 cm focal length be placed in order to form a real image of the

Last Answer : A source of light and a screen are placed 90 cm apart. Where should a convex lens of 20 cm focal ... form a real image of the source on the screen ?

A converging lens forms a three times magnified image of an object, which can be take on a screen. If the focal length of the lens is 30 cm, then the distance of the object from the lens is (a) - 55 cm (b) - 50 cm (c) - 45 cm (d) - 40 cm

Description : A converging lens forms a three times magnified image of an object, which can be take on a screen. If the focal length of the lens is 30 cm, then the distance of the object from the lens is (a) - 55 cm (b) - 50 cm (c) - 45 cm (d) - 40 cm

Last Answer : (d) - 40 cm