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The average size of an Indian face is 24...

The average size of an Indian face is `24xx16 cm^(2)`. Find the minimum size of a plane mirror required to see the face completely by :
(i) one eyed man
(ii) tow eyed man. (Distance between eyes is `=4 cm`)

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To find the minimum size of a plane mirror required to see the face completely for both a one-eyed man and a two-eyed man, we can follow these steps: ### Given: - Average size of an Indian face: 24 cm (height) x 16 cm (width) - Distance between the eyes: 4 cm ### (i) For a One-Eyed Man: 1. **Determine the Height of the Mirror:** - The minimum height of the mirror required to see the entire height of the face is half the height of the face. - Therefore, the minimum height of the mirror \( h_m \) is given by: \[ h_m = \frac{h}{2} = \frac{24 \, \text{cm}}{2} = 12 \, \text{cm} \] 2. **Determine the Width of the Mirror:** - For a one-eyed man, he can see only half the width of the face at a time. Therefore, the minimum width of the mirror \( w_m \) is: \[ w_m = \frac{w}{2} = \frac{16 \, \text{cm}}{2} = 8 \, \text{cm} \] 3. **Final Calculation for One-Eyed Man:** - The minimum size of the mirror required for a one-eyed man is: \[ \text{Size of mirror} = h_m \times w_m = 12 \, \text{cm} \times 8 \, \text{cm} \] ### (ii) For a Two-Eyed Man: 1. **Determine the Height of the Mirror:** - The height of the mirror remains the same as for the one-eyed man since it is based on the height of the face: \[ h_m = \frac{h}{2} = 12 \, \text{cm} \] 2. **Determine the Width of the Mirror:** - For a two-eyed man, he needs to see the entire width of the face. The distance between the eyes is 4 cm, so the mirror must be wide enough to reflect the entire width of the face. - The minimum width of the mirror \( w_m \) is equal to the width of the face: \[ w_m = 16 \, \text{cm} \] 3. **Final Calculation for Two-Eyed Man:** - The minimum size of the mirror required for a two-eyed man is: \[ \text{Size of mirror} = h_m \times w_m = 12 \, \text{cm} \times 16 \, \text{cm} \] ### Summary of Results: - **For One-Eyed Man:** Minimum size of mirror = \( 12 \, \text{cm} \times 8 \, \text{cm} \) - **For Two-Eyed Man:** Minimum size of mirror = \( 12 \, \text{cm} \times 16 \, \text{cm} \)

To find the minimum size of a plane mirror required to see the face completely for both a one-eyed man and a two-eyed man, we can follow these steps: ### Given: - Average size of an Indian face: 24 cm (height) x 16 cm (width) - Distance between the eyes: 4 cm ### (i) For a One-Eyed Man: ...
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The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about 2.5cm for a grown up person. A perosn can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around 25cm. A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image o the spectacle lens becomes object for the eye lens and whose image is formed on the retina. The number of spectacle lens used for th eremedy of eye defect is decided by the power fo the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is +3D (converging lens of focal length 100//3cm ), then number of lens will be +3 . For all the calculations required, you can use the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens. Q. A far sighted man connot see objects clearly unless they are at least 100cm from his eyes. The number of the spectacle lenses that will make his range of clear vision equal to an average grown up person will be

The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about 2.5cm for a grown up person. A perosn can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around 25cm. A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image o the spectacle lens becomes object for the eye lens and whose image is formed on the retina. The number of spectacle lens used for th eremedy of eye defect is decided by the power fo the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is +3D (converging lens of focal length 100//3cm ), then number of lens will be +3 . For all the calculations required, you can use the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens. Q. A near sighted man can clearly see ojects only upto a distance of 100cm and not beyond this. The number of the spectacle lenses necessary for the remedy of this defect will be

The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about 2.5cm for a grown up person. A perosn can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around 25cm. A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image o the spectacle lens becomes object for the eye lens and whose image is formed on the retina. The number of spectacle lens used for th eremedy of eye defect is decided by the power fo the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is +3D (converging lens of focal length 100//3cm ), then number of lens will be +3 . For all the calculations required, you can use the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens. Q. A person can see objects clearly from distance 10cm to oo . Then, we can say that the person is

The ciliary muscles of eye control the curvature of the lens in the eye and hence can alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about 2.5cm for a grown up person. A perosn can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around 25cm. A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image o the spectacle lens becomes object for the eye lens and whose image is formed on the retina. The number of spectacle lens used for th eremedy of eye defect is decided by the power fo the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is +3D (converging lens of focal length 100//3cm ), then number of lens will be +3 . For all the calculations required, you can use the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens. Q. Minimum focal length of eye lens of a normal peson is

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