Question : Can you write in blue color using a red ink pen

 

Answer is yes but how ?

The answer is no, but you can see blue from a red pen. State at the writing for ~30 seconds and then at a white surface and you will see a blu-ish afterimage, owing to retinal fatigue.

 

http://en.wikipedia.org/wiki/Afterimage

Yes, the paper can contain a material that, when interacting with red ink, turns blue, and so you'd effectively see blue writing from red ink.

Simple answer is yes,...in blue color.... in red color.. in black color..... :) read this ... this is written "in blue color"

So this being phrased as a scientific question was part of the setup, rather than saying it was a brain teaser?

Sir, a little chap troubled me with this question.......question and answer are both looks correct....This is why I posted in The Lounge ...

Yes: write your message in red ink, then accelerate it near the speed of light toward its recipient. The light from the message will be blue-shifted, and will in fact be blue at high enough speeds.