295.  Resolving power of a telescope depends on
A. the diameter of the aperture
B. the pupil aperture of the eye
C. the diameter of the object glass
D. all the above.

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296.  The longitudinal section of the surface of bubble tube is
A. straight
B. circular
C. parabolic
D. elliptic.

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297.  The bubble tube is nearly filled with
A. alcohol or chloroform
B. a liquid which is very mobile
C. a liquid having low freezing point
D. all the above.

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298.  The radius of curvature of the arc of the bubble tube is generally kept
A. 10 m
B. 25 m
C. 50 m
D. 100 m.

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299.  While rotating the theodolite in the horizontal plane, the bubble of the bubble tube takes up the same position in its tube, it indicates
A. the rotation axis is vertical
B. the trummion axis is horizontal
C. the line of collimation is perpendicular to vertical axis
D. none of the above

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300.  For high sensivity of the bubble tube
A. a liquid of low viscosity is used
B. a liquid of low surface tension is used
C. the bubble space should be long
D. all the above.

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301.  Pick up the correct statement from the following :
A. in the earth's magnetic field, a magnetic needle rests in magnetic meridian
B. the angle between the true meridian and the magnetic meridian is called magnetic variation
C. one end of the magnetic needle supported at its centre of gravity tends to dip down towards the nearer magnetic pole of the earth
D. all the above.

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