A convex lens with a focal length of 12 cm has an object at a distance of 20 cm in front of the lens. A blurred image is obtained on the screen placed at a distance of 23 cm in front of the lens. In order to obtain a clear image, the screen has to be moved:

Answer: B. away from the lens

Given values:
Focal length (f) = +12 cm
Object distance (u) = -20 cm
Apply the Lens Formula:
1/v - 1/u = 1/f
1/v - 1/(-20) = 1/12
1/v + 1/20 = 1/12
1/v = 1/12 - 1/20
1/v = (5 - 3)/60 = 2/60
v = +30 cm
Conclusion:The sharp image forms at 30 cm. Since the screen is currently at 23 cm, it must be moved away from the lens to reach the 30 cm position.

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