Cosmic background radiation is electromagnetic radiation from the sky with no discernible source. The origin of this radiation depends on the region of the spectrum that is observed. 
        
                    
             
        
        
        
Answer:
Invisible UV energy reacts with emulsion sensitizer and hardens the stencil so it won't dissolve with water and rinse down the drain
Explanation:
 
        
             
        
        
        
1 Joule IS 1 newton-meter.