Question Discussion & Solution

The correct answer is Curvature of the lens.

Important Points

• Focal length of a lens depends on its curvature and the medium outside the lens.

Additional Information

• The ability of a lens to converge or diverge light rays depends on its focal length.
  • For example, a convex lens of short focal length bends the light rays through large angles, by focussing them closer to the optical centre.
  • Similarly, the concave lens of a very short focal length causes a higher divergence than the one with a longer focal length.
• The degree of convergence or divergence of light rays achieved by a lens is expressed in terms of its power.
  • The power of a lens is defined as the reciprocal of its focal length.

The pattern followed here is as follows,

Hence, X is in North-west of C.

The correct answer is Input.

• Devices that enter information into the computer and communicate with it are called Input devices.

Key Points

• An input device is a peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance.
• The Central Processing Unit (CPU) of a computer receives the input and processes it to produce the output.

Additional Information

• Examples of input devices include
  • Keyboards, mouse, scanners, digital cameras, joysticks, Microphone, TouchPad, Webcam, remote, biometric devices, etc.
• Keyboard is a basic input device that is used to enter data into a computer or any other electronic device by pressing keys.
• Mouse is a hand-held input device that is used to move cursor or pointer across the screen. 
• Scanner uses the pictures and pages of text as input.