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Dear student,

You are asking if the focal length of a lens is 20 cm, what is its power in diopters?

Calculating Lens Power:

• Power of a lens is defined as the reciprocal of its focal length when expressed in meters
• The unit of power of a lens is diopter (D)

Formula:

• Power (P) = 1 / focal length (in meters)

Given:

• Focal length (f) = 20 cm = 0.2 meters

Calculation:

• Power (P) = 1 / 0.2 = 5 diopters

Therefore, the power of the lens is +5 diopters

Why is it positive?

• A positive power indicates a convex lens (converging lens)
• Convex lenses are thicker at the center and thinner at the edges
• They converge light rays to a point called the focus

convex lens

Additional Notes:

• Concave Lens: If the lens were concave (diverging lens), the power would be negative
• Units: Always ensure that the focal length is converted to meters before calculating the power in diopters

Therefore, if a lens has a focal length of 20 cm, its power is +5 diopters. This means it is a convex lens capable of converging light rays.

Dear Abhay Pratap Singh,

Yes, Rameshwaram Institute of Technology & Management offers placement for B.tech in Computer Science. The Rameshwaram Institute of Technology and Management Lucknow Placement Cell is looking forward to the placement process as an important component of the institute. They worked hard to advance the kids and prepare them for the industry. RITM provides a regular calendar of events that provide students with business experiences, such as grooming, soft skills training, IT exposure, industrial tours, seminars, guest speakers, and technical events and contests. The top recruiters for RITM B.Tech CS placements are Infosys, TCS, Exide, Amararaja, ICICI, HDFC, Bajaj Motors, Vivo, Maruti, HCL and etc.

I hope this was helpful! 

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