What is lumen? Its relation with watt

Lumen:

Let me google that for you (http://www.lmgtfy.com/?q=Lumen)

Watt:

Let me google that for you (http://www.lmgtfy.com/?q=Watt)

You will find that a lumen is a measurement of light, and that watt is a measurement of electric power, and there is no direct relationship between either.

Light sources have widely varying efficencies for delivering light. Go here Bulbs at a Glance (http://www.megavolt.co.il/Tips_and_info/bulbs_at_glance.html) for information about lumens per watt.