I think it is "A'' 'It moves along straight lines in air and changes direction when it enters water.
        
                    
             
        
        
        
Answer:
Mutual inductance will be 
Explanation:
We have given induced current 
Time is given as 
We have to find the mutual inductance between the coils 
Induced emf is given as e = 9 volt
We know that induced emf is given by 


 
 
 
        
             
        
        
        
Answer:
Explanation:
Let the intensity of the noise be represented by I
Given that
40dB = 10 log 10  ( I /I•) ........ 1
I• is the lowest or threshold intensity of sound made.
I represents the intensity of the sound/ noise
The intensity of noise of 1000flies will be 
 β = 10 log 10 (1000I/I•)
Open up the bracket
 β = 10 log 10(1000)+ 10 log 10(I/I•)
10 log 10(10^3)+10 log 10(I/I•)
3×10(10 log 10) +10 log 10(I/I•)
Recall, 10 log 10 = 1
30×1 + 10 log 10(I/I•).........2
Put equation 1 into 2
 β =30+40
 = 70db
 
        
             
        
        
        
Newton's third law states "for every action, there is an equal and opposite reaction."
What this is pretty much saying is that for every action, there is a consequence. One force connects and triggers another.
        
                    
             
        
        
        
Specific heat.  The definition of specific heat is the amount of energy required to raise the temperature of 1g of a substance by 1K or 1°C.