According to the New Cartesian Sign Convention, which one of the following is correct is respect of the formula \(\dfrac{1}{f} = \dfrac{1}{v}+ \dfrac{1}{u}\), where symbols have their usual meanings?
1
It applies only to spherical mirrors
2
It applies only to spherical lenses
3
It applies to spherical mirrors as well as spherical lenses
4
It is an invalid formula