Question

explain what is optical path length . how is different from actual path length​

Answer 1

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➦ᴅᴏ=ɴ×ᴅɢ ᴡʜᴇʀᴇ ᴅᴏ ɪs ᴛʜᴇ ᴏᴘᴛɪᴄᴀʟ ᴘᴀᴛʜ ʟᴇɴɢᴛʜ, ɴ ɪs ᴛʜᴇ ʀᴇғʀᴀᴄᴛɪᴠᴇ ɪɴᴅᴇx ᴏғ ᴛʜᴇ ᴍᴇᴅɪᴜᴍ ᴀɴᴅ ᴅɢ ɪs ᴛʜᴇ ᴀᴄᴛᴜᴀʟ ᴘᴀᴛʜ ʟᴇɴɢᴛʜ ᴏʀ ᴛʜᴇ ɢᴇᴏᴍᴇᴛʀɪᴄ. Aᴄᴛᴜᴀʟ ᴘᴀᴛʜ ʟᴇɴɢᴛʜ ᴏʀ Gᴇᴏᴍᴇᴛʀɪᴄ ʟᴇɴɢᴛʜ ɪs sɪᴍᴘʟʏ ᴛʜᴇ ʀᴇᴀʟ ʟᴇɴɢᴛʜ ᴛʀᴀᴠᴇʟʟᴇᴅ ʙʏ ᴛʜᴇ ʟɪɢʜᴛ ɪɴ ᴛʜᴇ ᴍᴇᴅɪᴜᴍ.

Explanation:

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Answer 2

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do=n×dg where do is the optical path length, n is the refractive index of the medium and dg is the actual path length or the geometric. Actual path length or Geometric length is simply the real length travelled by the light in the medium.