Answer:
The visible light frequency is 400 THz to 700 THz, approximately. A THz is a Terahertz, which is a unit of frequency equal to one trillion Hertz.
 
        
             
        
        
        
The frequency of the wave is 4 Hz
        
             
        
        
        
C. Negative force. The dog isn't going to learn that way.
        
             
        
        
        
Answer:
276 days
Explanation:
1/4 th of the original means <u><em>2 half lives</em></u>
1 half life = 138 days
So, 
2 half lives = 276 days
 
        
             
        
        
        
Answer:
Explanation: It is halved