PhysicsMedium105×since 2002Q7047The thickness at the centre of a plane convex lens is 3 mm and the diameter is 6 cm. If the speed of light in the material of the lens is 2 ×\times× 10⁸ ms^−-−1. The focal length of the lens is ____________.A0.30 cmB30 cmC15 cmD1.5 cmCheck answerSkip