The focal length of a thin lens is given by f= - 10 cm . Is the lens concave or convex?

Focal length of thin lens ......

What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.

The focal length of the eye lens is changed due to the action of the……….

The focal length of the lens in a photographic camera is 5cm. what is the power of the lens?

Focal length of thin lens of refractive index 1.5 is 15 cm. When placed on liquid of refractive index 4/3 , then its focal length will be ...... cm.

The change in focal length of an eye lens is caused by the action of the …

A point source of light is kept at a distance of 15cm from a converging lens,on its optical axis.The focal length of the lens is 10cm and its diameter is 3cm ,A screen is placed on the other side of the lens ,perpendicular to the axis of lens,at a distance 20cm from it.Then find the area of the illuminated part of the screen?

In a displacement method the distance between the object and the screen is 70 cm and the focal length of the lens is 16 cm, find the separations of the magnified and diminished image position of the lens.