Magnification of a real image Essay Sample

Title: To analyze the magnification of a existent image by a convex lens. Aim: To find the focal length of a convex lens.
Apparatus and Materials:
1. Light box
2. Convex lens
3. Plasticine
4. Meter regulation
5. Screen
6. Short transparent swayer
Apparatus:
1. Put up the setup as shown in Figure 4-1.

Figure 4-1
Theory:
From the lens equation:

Where:
P = object distance
Q = image distance

Linear magnification.

Procedure:
1. The setup was set up as in Figure 4-1.
2. The light beginning was switched on.
3. A length of “1cm” on the graduated table of the crystalline swayer was chose as the object. hence object size. y = 1cm. 4. A value for the object distance. P was set. The image distance was adjusted until a crisp image was obtained on the screen. 5. The image distance. Q was measured.

6. The length. y’ or size of the “1cm” image was measured. 7. The magnitude of the additive magnification. m was found for each image where.
8. The object distance was varied. stairss 4 to 7 was repeated. and seven ( 7 ) sets of readings of p. q. y’ and m was obtained. 9. The readings of
p. q. y’ and m was tabulated.
10. A graph of m against Q was plotted.
11. The gradient of the graph was determined.
12. The focal length. degree Fahrenheit of the lens was calculated.

Datas:
Size of object. y = ( 2. 60 ± 0. 10 ) centimeter
Object distance. P ± 0. 10cm| Image distance. q ± 0. 10 cm| Size of image. y’ ± 0. 10 cm| Magnification. m = y’/y| 15. 0| 30. 0| 5. 20| 2. 00|
20. 0| 20. 0| 2. 70| 1. 00|
25. 0| 16. 7| 1. 70| 0. 70|
30. 0| 15. 0| 1. 30| 0. 50|
35. 0| 14. 0| 1. 00| 0. 40|
40. 0| 13. 3| 0. 80| 0. 30|
45. 0| 12. 9| 0. 60| 0. 20|

Calculation:

Mean of image distance. q=30. 0+20. 0+16. 70+15. 0+14. 0+13. 3+12. 97 = 121970
= 17. 41 centimeter #

Mean of magnification. m. =2. 00+1. 00+0. 70+0. 50+0. 40+0. 30+0. 207 = 5170
=0. 73 centimeter #

Centroid = ( 17. 41. 0. 73 ) #

Datas Analysis:
| Linear Least Squares Fits| | | | |
| | | | | | | | |
| x| y| xy| x^2| Sx| Sx + c| Y – ( Sx + degree Celsius ) | [ Y – ( Sx + degree Celsius ) ] ^2| 1| 30. 000| 2. 000| 60. 0000| 900. 0000| 3. 0692| 2. 0162| -0. 0162| 0. 0003| 2| 20. 000| 1. 000| 20. 0000| 400. 0000| 2. 0461| 0. 9931| 0. 0069| 0. 0000| 3| 16. 700| 0. 700| 11. 6900| 278. 8900|
1. 7085| 0. 6555| 0. 0445| 0. 0020| 4| 15. 000| 0. 500| 7. 5000| 225. 0000| 1. 5346| 0. 4816| 0. 0184| 0. 0003| 5| 14. 000| 0. 400| 5. 6000| 196. 0000| 1. 4323| 0. 3793| 0. 0207| 0. 0004| 6| 13. 300| 0. 300| 3. 9900| 176. 8900| 1. 3607| 0. 3077| -0. 0077| 0. 0001| 7| 12. 900| 0. 200| 2. 5800| 166. 4100| 1. 3198| 0. 2667| -0. 0667| 0. 0045| 8| | | | | | | | |

9| | | | | | | | |
10| | | | | | | | |
11| | | | | | | | |
12| | | | | | | | |
?| 121. 900| 5. 100| 111. 3600| 2343. 1900| | | | 0. 0076| | | | | | | | | |
| n =| 7| | | ? =| 0. 0389| | |
| | | | | | | | |
| S =| 0. 1023| | | ? ( S ) =| 0. 0026| | |
| | | | | | | | |
| degree Celsius =| -1. 0530| | | ? ( degree Celsius ) =| 0. 0480| | |
f=1S= 10. 1023 =9. 775 cm | ? f = ? ( S ) S ?f = 0. 0260. 1023 ? 9. 775 cm =0. 2484 cm| fexp=9. 775 ±0. 25 cm| Known focal length. fk=10. 00 cm| % error= f exp- fkfk ?100 % = 9. 775-10. 0010. 00 ?100 % =2. 25 % | Percentage Error=2. 25 % |

Consequences:
The focal length of the convex lens was found to be f = ( 9. 775 ± 0. 25 ) centimeter with a per centum mistake of 2. 25 % Discussion:
A convex lens ( meeting lens ) is a round glass home base convex on both surfaces. The non-uniform thickness causes bending of light towards the rule axis. In peculiar. a convex lens converges visible radiation from eternity analogue to the chief axis to a point. called the focal point ( degree Fahrenheit ) . Light beams from eternity non parallel to the chief axis are converged to the focal plane. When an object in placed at the placed at the focal point. degree Fahrenheit of the convex lens. the emerging visible radiation would be parallel to the chief axis. If a plane mirror placed on the other side of the lens. the beams reflected by the plane mirror would follow the original way and the concluding image would happen at the same place as the object. The distance between the object and the lens gives the focal length of the convex lens. An object placed beyond degree Fahrenheit from the lens would bring forth a existent image.

In this experiment. it will capture the existent image of an lighted object on a screen. The convex lens was held confronting distant objects. The screen on the other side of the lens was moved until the images of distant object were focused on the screen. The distance between the lens and the screen was measured. This gave the focal length degree Fahrenheit of the lens. When light beams enter a piece of glass. they refract. or flex. because the velocity at which they are going alterations. If the glass is shaped certain ways. the image that consequences from the light’s transition can look larger. smaller. closer. or farther off than the original object. The chief axis is the line that joins the centres of curvature of its surfaces. The focal point is the point where a beam of light analogues to the chief axis converges. The focal length is the distance from the centre of the lens to the focal point. A convex. or meeting. lens is thicker in the center than on the terminals. Parallel light beams will run into at a point beyond the lens. The attendant image with a convergence ( convex ) lens is dependent upon the comparative places of the object. the lens. and the screen when the image is existent. The lens equation that relate the focal length. object distance. and image distance is: 1f= 1p+1q

The magnification of the lens refers to the ratio of the image size to that of the object: M=y’y= -qp The len that usage in this experiment are bi-convex. intending it is thicker at the centre than at the fringe. Since the image appears to be on the same side of the lens as the object. it can non be projected onto a screen. Such images are termed practical images and they appear unsloped. non upside-down. Light reflected from the object enters the len in consecutive lines as illustrated. Light from an object that is really far off from the forepart of a convex len will be brought to a focal point at a fixed point behind the lens. This is known as the focal point of the lens. The distance from the centre of the convex lens to the focal plane is know as the focal distance. The image of object will appears at the focal plane. The image is smaller than the object. If the object is now moved closer to the forepart of the lens but is still more than two focal lengths in forepart of the len. If the image is found farther behind the len.

It is larger than the one described above. but is still smaller than the object. The image is inverted. and is a existent image. If the object is brought to twice the focal distance in forepart of the lens. The image is now two focal lengths behind the lens as illustrated. It is the same size as the object ; it is existent and inverted. If the object is situated at the front focal plane of the convex lens. In this instance. the beams of light emerge from the lens in analogue. The image is located on the same side of the lens as the object. and it appears unsloped. The image is a practical image and appears. While the size of the object was so determined to be fixed as the 1cm graduated table on the crystalline swayer to guarantee a clear computation and measurings to be taken. It is non advisable to alter the object size throughout the experiment as it affects the computation and enhances disagreement.

Following. few guidelines were used to find the correct or optimum image distance. This can be done by seting the screen off or toward the lens until a clear crisp image can be seen on the screen. The optimum image is obtained when there were no blurry lines around the image’s border and the country between dark and light parts are clearly defined.

The graph of this experiment is a additive graph and it is same as our predicted. Furthermore. it is a straight relative. This is because the magnification. thousand addition. the distance of image. Q additions. while the focal point length. f lessenings. The gradient. S of this experiment is 0. 1023. Whereas the focal point length of the convergence lens is 1S = 9. 775 centimeter.

There is a speedy manner to gauge the focal length of a convex lens without transporting out any computations. Holded the convex lens up to oculus and expression at something far off. when the image goes wholly bleary means that the lens about at its focal length off from the oculus. First. utilize the scene which is merely opposite to the object. 1cm graduated table of crystalline swayer. Second. holded a metre regulation to face and against to the scene. Third. holded the convex lens onto the metre regulation and slide easy towards the scene until acquire a crisp and clear image on the scene. Last. step the length between the convex lens and the centre point of the scene and convex lens. The graduated table was the estimation focal length.

We took attention to guarantee the image was in sharpest and concentrate plenty to avoid the possibility of mensurating a “virtual image” alternatively. Hence. reiterate each clip and acquire an norm. Ensure that the lens. object and screen were all placed in a consecutive line. Parallax mistakes associated with measurement and guarantee the line of sight is at right angles to the meter regulation. Take all measurings from the Centre of the lens and concentrate the image of a distant object onto a screen. Measure the distance between the lens and the screen. This corresponds to an approximative value for the focal length of the lens. Guarantee the oculus must put perpendicular to the meter regulation before taking readings. A darkened room was used to cut down ambient visible radiation that could hold distracted from the image itself.

Decision:

As a decision we can reason. the magnification of the tranparent swayer is directlyproportional to the distance of the image.