In a common-emitter amplifier, the load resistance of the output circuit is 1000 times the resistance of the input circuit. If α = 0.98, then voltage gain is
49 × 103
2.5 × 102
1.5 × 102
4.9
The plane faces of two identical plano-convex lenses each having a focal length of 50 cm are placed against each other to form a usual biconvex lens. The distance from this lens combination at which an object must be placed to obtain a real, inverted image which has the same size as the object is
50 cm
25 cm
100 cm
40 cm
A.
50 cm
The focal length of the combination is
Given, f1 = 50 cm, f2 = 50 cm
Object when placed at centre of curvature forms a real, inverted image of same size as object = (2 x 25 = 50 cm).