CUET Preparation Today
Two thin lenses of power +3D and -1D are held in contact with each other. Focal length of the combination would be: |
5 m 50 cm 10 m 100 cm |
50 cm |
The correct answer is Option (2) → 50 cm The power (P) of a combination of lenses is - $P=P_1+P_2$ where, $P_1=+3D$ and $P_2=-1D$ $⇒P=3D-1D=2D$ Now, $P=\frac{100}{f(in\,cm)}⇒f=\frac{100}{2}=50cm$ |
