A pencil is placed upright at a distance of 10 cm from a convex lens of focal length 15 cm. The nature of the image of the pencil will be
real, inverted and magnified
real, erect and magnified
virtual, erect and reduced
virtual, erect and magnified
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-1 – 2016
For a convex lens, when the object is placed between the optical centre and the principal focus (i.e., 0 < |u| < f, or 0 < 10 cm < 15 cm), the image formed is virtual, erect, and magnified.
– Object between optical centre and F: Image is virtual, erect, magnified, and on the same side as the object.
1/15 = 1/v – 1/(-10)
1/15 = 1/v + 1/10
1/v = 1/15 – 1/10 = (2 – 3)/30 = -1/30
v = -30 cm.
Since v is negative, the image is virtual and formed on the same side as the object.
Magnification m = v/u = -30 / -10 = +3.
Since m is positive, the image is erect. Since |m| > 1, the image is magnified.
Thus, the image is virtual, erect, and magnified.