Question

if focal length decrease by 20% then how many % decrease in power ?​

Answer 1

Answer:

400 ᴍᴇɴ x 50 ᴅᴀyꜱ = 20000 (ᴛᴏᴛᴀʟ ꜰᴏᴏᴅ)

ᴛʜɪꜱ ɪꜱ yᴏᴜʀ ꜱᴛᴀɴᴅᴀʀᴅ ᴇqᴜᴀᴛɪᴏɴ ꜰᴏʀ ᴛᴏᴛᴀʟ ꜰᴏᴏᴅ.

ɴᴏᴡ, ꜰᴏʀ 20 ᴅᴀyꜱ, 400 ᴍᴇɴ ᴡɪʟʟ ᴇᴀᴛ:

20 x 400 = 8000

ꜰᴏᴏᴅ ʟᴇꜰᴛ = 12000.

ᴍᴇɴ ʟᴇꜰᴛ = 300

300 x ɴᴏ. ᴏꜰ ᴅᴀyꜱ = 12000

ɴᴏ. ᴏꜰ ᴅᴀyꜱ = 12000/300

= 40

Answer 2

Hey user, your answer will be 40%

Because microscope will decrease but that of telescope will increase.