Question

emissivity of perfectly​

Answer 1

Step-by-step explanation:

ᴛʜᴇ ᴇᴍɪssɪᴠɪᴛʏ ᴏғ ᴛʜᴇ sᴜʀғᴀᴄᴇ ᴏғ ᴀ ᴍᴀᴛᴇʀɪᴀʟ ɪs ɪᴛs ᴇғғᴇᴄᴛɪᴠᴇɴᴇss ɪɴ ᴇᴍɪᴛᴛɪɴɢ ᴇɴᴇʀɢʏ ᴀs ᴛʜᴇʀᴍᴀʟ ʀᴀᴅɪᴀᴛɪᴏɴ. ᴛʜᴇʀᴍᴀʟ ʀᴀᴅɪᴀᴛɪᴏɴ ɪs ᴇʟᴇᴄᴛʀᴏᴍᴀɢɴᴇᴛɪᴄ ʀᴀᴅɪᴀᴛɪᴏɴ ᴛʜᴀᴛ ᴍᴀʏ ɪɴᴄʟᴜᴅᴇ ʙᴏᴛʜ ᴠɪsɪʙʟᴇ ʀᴀᴅɪᴀᴛɪᴏɴ (ʟɪɢʜᴛ) ᴀɴᴅ ɪɴғʀᴀʀᴇᴅ ʀᴀᴅɪᴀᴛɪᴏɴ, ᴡʜɪᴄʜ ɪs ɴᴏᴛ ᴠɪsɪʙʟᴇ ᴛᴏ ʜᴜᴍᴀɴ ᴇʏᴇs. ᴛʜᴇ ᴛʜᴇʀᴍᴀʟ ʀᴀᴅɪᴀᴛɪᴏɴ ғʀᴏᴍ ᴠᴇʀʏ ʜᴏᴛ ᴏʙᴊᴇᴄᴛs (sᴇᴇ ᴘʜᴏᴛᴏɢʀᴀᴘʜ) ɪs ᴇᴀsɪʟʏ ᴠɪsɪʙʟᴇ ᴛᴏ ᴛʜᴇ ᴇʏᴇ. ǫᴜᴀɴᴛɪᴛᴀᴛɪᴠᴇʟʏ, ᴇᴍɪssɪᴠɪᴛʏ ɪs ᴛʜᴇ ʀᴀᴛɪᴏ ᴏғ ᴛʜᴇ ᴛʜᴇʀᴍᴀʟ ʀᴀᴅɪᴀᴛɪᴏɴ ғʀᴏᴍ ᴀ sᴜʀғᴀᴄᴇ ᴛᴏ ᴛʜᴇ ʀᴀᴅɪᴀᴛɪᴏɴ ғʀᴏᴍ ᴀɴ ɪᴅᴇᴀʟ ʙʟᴀᴄᴋ sᴜʀғᴀᴄᴇ ᴀᴛ ᴛʜᴇ sᴀᴍᴇ ᴛᴇᴍᴘᴇʀᴀᴛᴜʀᴇ ᴀs ɢɪᴠᴇɴ ʙʏ ᴛʜᴇ sᴛᴇғᴀɴ–ʙᴏʟᴛᴢᴍᴀɴɴ ʟᴀᴡ. ᴛʜᴇ ʀᴀᴛɪᴏ ᴠᴀʀɪᴇs ғʀᴏᴍ 0 ᴛᴏ 1. ᴛʜᴇ sᴜʀғᴀᴄᴇ ᴏғ ᴀ ᴘᴇʀғᴇᴄᴛ ʙʟᴀᴄᴋ ʙᴏᴅʏ (ᴡɪᴛʜ ᴀɴ ᴇᴍɪssɪᴠɪᴛʏ ᴏғ 1) ᴇᴍɪᴛs ᴛʜᴇʀᴍᴀʟ ʀᴀᴅɪᴀᴛɪᴏɴ ᴀᴛ ᴛʜᴇ ʀᴀᴛᴇ ᴏғ ᴀᴘᴘʀᴏxɪᴍᴀᴛᴇʟʏ 448 ᴡᴀᴛᴛs ᴘᴇʀ sǫᴜᴀʀᴇ ᴍᴇᴛʀᴇ ᴀᴛ ʀᴏᴏᴍ ᴛᴇᴍᴘᴇʀᴀᴛᴜʀᴇ (25 °ᴄ, 298.15 ᴋ); ᴀʟʟ ʀᴇᴀʟ ᴏʙᴊᴇᴄᴛs ʜᴀᴠᴇ ᴇᴍɪssɪᴠɪᴛɪᴇs ʟᴇss ᴛʜᴀɴ 1.0, ᴀɴᴅ ᴇᴍɪᴛ ʀᴀᴅɪᴀᴛɪᴏɴ ᴀᴛ ᴄᴏʀʀᴇsᴘᴏɴᴅɪɴɢʟʏ ʟᴏᴡᴇʀ ʀᴀᴛᴇs.

Answer 2

Step-by-step explanation:

Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a a perfect emitter, known as a blackbody, at the same temperature and wavelength and under the same viewing conditions.