Question

why we see face in a mirror but not in a glass piece​

Answer 1

because a mirror is a transparent material but one side was cover by a surface and glass piece was all type transparent

Answer 2

$\huge \boxed{ \fcolorbox{blue}{pink}{คหรωεя}}$

ɪɴ ɴᴏʀᴍᴀʟ ᴍɪʀʀᴏʀs ʟɪɢʜᴛ ʀᴀʏs ᴀʀᴇ ʀᴇғʟᴇᴄᴛᴇᴅ ʙᴀᴄᴋ ᴛᴏᴡᴀʀᴅs ᴍɪʀʀᴏʀ ᴀғᴛᴇʀ ɪᴛ ɪɴᴄɪᴅᴇɴᴛs ᴏɴ ᴏᴜʀ ғᴀᴄᴇ, ᴛʜᴇ ᴍɪʀʀᴏʀ ᴀɢᴀɪɴ ʀᴇғʟᴇᴄᴛs ʙᴀᴄᴋ ᴛʜᴇ ʟɪɢʜᴛ ᴀɴᴅ ᴏᴜʀ ᴇʏᴇs ᴀʙsᴏʀʙ ɪᴛ ᴛʜᴜs ᴡᴇ ᴄᴀɴ sᴇᴇ ᴏᴜʀ ɪᴍᴀɢᴇ. sɪɴᴄᴇ ᴛʜᴇʀᴇ ɪs ɴᴏ ʀᴇғʟᴇᴄᴛɪᴏɴ ᴏғ ʟɪɢʜᴛ ғʀᴏᴍ ɢʟᴀss ᴘᴀɴᴇ ᴛʜᴇʀᴇ ɪsɴᴏ ɪᴍᴀɢᴇ.