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If the focal length of the objective len...

If the focal length of the objective lens is increased then

A

microscope will increase but that of telescope decrease.

B

microscope and telecope both will increase.

C

microcope and telescope both will decrease.

D

microscope will decrease but that of telescope will increase.

Text Solution

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The correct Answer is:
D
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Read the following paragraph and answer the following questions given below it : Construction of a compound microscope : (i) Acompound microscope consists of a metal tube fitted with two convex lenses at the two ends. These lenses are called the objective lens ( the lens directed towards the object ) and the eyepiece ( the lens directed towards the eye ). Both the lenses are small in size , but the cross section of the objective lens has a short focal length . the focal length of the eyepiece is more than that of the objective lens . (ii) The metal tube is mounted on a stand . thr principal axes of the objective lens and the eyepiece are along the same line . The distance between the object and objective lens can be changed with a screw . It is possible to change the distance between the objective lens and the eyepiece. Working : (i) The object to be observed is illuminated and placed in front of the objective lens. slightly beyond the focal length of the objective lens. it's real , inverted and enlarged image is formed by the objective lens on the other side. (ii) This intermediate image lies with in the focal length of the eyepiece. It serves as an object for the eyepiece. The eyepiece works as a simple microscope . the final image is virtual, highly enlarged and inverted with respect to the original object . It can be formed at the minimum distance of distinct vision from the eyepiece . The final image is observed by keeping the eye close to the eyepiece. Use: This microscope is used to observe blood cells , microorganisms , etc. In a compound microscope , which lens has greater focal length ?

Read the following paragraph and answer the following questions given below it : Construction of a compound microscope : (i) Acompound microscope consists of a metal tube fitted with two convex lenses at the two ends. These lenses are called the objective lens ( the lens directed towards the object ) and the eyepiece ( the lens directed towards the eye ). Both the lenses are small in size , but the cross section of the objective lens has a short focal length . the focal length of the eyepiece is more than that of the objective lens . (ii) The metal tube is mounted on a stand . thr principal axes of the objective lens and the eyepiece are along the same line . The distance between the object and objective lens can be changed with a screw . It is possible to change the distance between the objective lens and the eyepiece. Working : (i) The object to be observed is illuminated and placed in front of the objective lens. slightly beyond the focal length of the objective lens. it's real , inverted and enlarged image is formed by the objective lens on the other side. (ii) This intermediate image lies with in the focal length of the eyepiece. It serves as an object for the eyepiece. The eyepiece works as a simple microscope . the final image is virtual, highly enlarged and inverted with respect to the original object . It can be formed at the minimum distance of distinct vision from the eyepiece . The final image is observed by keeping the eye close to the eyepiece. Use: This microscope is used to observe blood cells , microorganisms , etc. Where do you place the object to be observed with a compound microscope ?

Read the following paragraph and answer the following questions given below it : Construction of a compound microscope : (i) Acompound microscope consists of a metal tube fitted with two convex lenses at the two ends. These lenses are called the objective lens ( the lens directed towards the object ) and the eyepiece ( the lens directed towards the eye ). Both the lenses are small in size , but the cross section of the objective lens has a short focal length . the focal length of the eyepiece is more than that of the objective lens . (ii) The metal tube is mounted on a stand . thr principal axes of the objective lens and the eyepiece are along the same line . The distance between the object and objective lens can be changed with a screw . It is possible to change the distance between the objective lens and the eyepiece. Working : (i) The object to be observed is illuminated and placed in front of the objective lens. slightly beyond the focal length of the objective lens. it's real , inverted and enlarged image is formed by the objective lens on the other side. (ii) This intermediate image lies with in the focal length of the eyepiece. It serves as an object for the eyepiece. The eyepiece works as a simple microscope . the final image is virtual, highly enlarged and inverted with respect to the original object . It can be formed at the minimum distance of distinct vision from the eyepiece . The final image is observed by keeping the eye close to the eyepiece. Use: This microscope is used to observe blood cells , microorganisms , etc. State which distance is adjusted to observe the object with a compound microscope ?

Read the following paragraph and answer the following questions given below it : Construction of a compound microscope : (i) Acompound microscope consists of a metal tube fitted with two convex lenses at the two ends. These lenses are called the objective lens ( the lens directed towards the object ) and the eyepiece ( the lens directed towards the eye ). Both the lenses are small in size , but the cross section of the objective lens has a short focal length . the focal length of the eyepiece is more than that of the objective lens . (ii) The metal tube is mounted on a stand . thr principal axes of the objective lens and the eyepiece are along the same line . The distance between the object and objective lens can be changed with a screw . It is possible to change the distance between the objective lens and the eyepiece. Working : (i) The object to be observed is illuminated and placed in front of the objective lens. slightly beyond the focal length of the objective lens. it's real , inverted and enlarged image is formed by the objective lens on the other side. (ii) This intermediate image lies with in the focal length of the eyepiece. It serves as an object for the eyepiece. The eyepiece works as a simple microscope . the final image is virtual, highly enlarged and inverted with respect to the original object . It can be formed at the minimum distance of distinct vision from the eyepiece . The final image is observed by keeping the eye close to the eyepiece. Use: This microscope is used to observe blood cells , microorganisms , etc. State the nature of the final image in a compound microscope relative to the object ?

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