How to get mime type from file name

Hello, Is there any function where I can pass a file name like "file.png" and get return the string of its type 'image/png' ? Basically it is a funcion that takes a file name and returns a string of its mime type. I have used mime_mail to send attachments but the I need when I am attaching the file to know its mime type, for instance a zip file or a jpg or a txt etc. Thanks in advance for the help.