Question

what is the focus length​

Answer 1

Answer:

The length between focus and pole is known as focul length

Explanation:

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Answer 2

THE FOCAL LENGTH OF AN OPTICAL SYSTEM IS A MEASURE OF HOW STRONGLY THE SYSTEM CONVERGES OR DIVERGES LIGHT; IT IS THE INVERSE OF THE SYSTEM'S OPTICAL POWER. A POSITIVE FOCAL LENGTH INDICATES THAT A SYSTEM CONVERGES LIGHT, WHILE A NEGATIVE FOCAL LENGTH INDICATES THAT THE SYSTEM DIVERGES LIGHT.

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