5. A dumpy level was set up at the midpoint between two pegs A and B, 50 m apart and the staff readings at A and B were 1.22 and 1.06. With the level set up a A, the readings at A and B were 1.55 and 1.37. The collimation error per 100 m length of sight is
7. Pick up the correct statement from the following :
Options
A. in astronomical telescope, the rays from the object after refraction at the objective are brought to a focus before entering the eyepiece to produce a real inverted image in front of the eye piece
B. in Galileo's telescope, the rays from the object get refracted at the objective and are intercepted by the eyepiece before a real image is formed
C. a line passing through the optical centre of the objective traversing through the eyepiece, is called line of sight
D. the line of sight which passes through the intersection of cross-lines marked on a diaphragm fixed in front of the eyepiece in a plane at right-angles to the axis, is called the line of collimation
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