3. A dumpy level is set up with its eye-piece vertically over a peg A. The height from the top of peg A to the centre of the eye-piece is 1.540 m and the reading on peg B is 0.705 m. The level is then setup over B. The height of the eye-piece above peg B is 1.490 m and a reading on A is 2.195 m. The difference in level between A and B is
5. Pick up the correct specification of Ramsden eyepiece from the following :
Options
A. it consists of two equal piano convex lenses
B. the curved surfaces of plano-convex lenses face each other
C. the two lenses are separated by a distance equal to 2/3 of the focal length of either lens.
D. the distance between the diaphragm and the front lens of the eyepiece is kept equal to 1/4 th of the focal length of a lens so that rays from a point on the diaphragm enter the eye as a parallel beam
8. 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
10. 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