Answer:
Explanation:
magnetic field due to circular wire 
= μ₀ i / 2r 
i is current and r is radius of coil .
Magnetic fields due to inner coil 
μ₀ x 20 / (2 x 9.5 x 10⁻²)
Magnetic field due to outer coil 
= μ₀ x I / (2 x 19 x 10⁻²) , I is the current to be calculated
Total field 
μ₀ x 20 /( 2 x 9.5 x 10⁻²) +μ₀ x I / (2 x 19 x 10⁻²)  = 0 
20 + I /2 = 0
I = - 40 A 
Current required is 40 A , and it will be in opposite direction. 
 
        
             
        
        
        
Neither set of choices is correct.
If the distance is tripled, then the forces decrease to
 1/9 Fg. and. 1/9 Fe.
Note. When the objects are charged, the gravitational force Fg can almost always be ignored, since Fe is like 10^40 greater when the quantities of mass and charge are similar.
        
             
        
        
        
Answer:
 The equation which describes conservation of charge is 
Explanation:
The law of conservation charge states that for an isolated system that sum of initial charges is equal to sum of final charges, that is the total charge is conserved.
let the sum of initial charges = 
let the sum of the final charges = 

Therefore, the equation which describes conservation of charge is 
 
        
             
        
        
        
Answer:
a) 665 kg.m/s
b) 2.97 kN
Explanation:
The impulse is given by:

where
va=velocity after
vb=velocity before
The velocity just before is given by:

The velocity just after is zero because there wasn't a rebound.
So the impulse is:

The impulse is also given by:

 
        
             
        
        
        
The same number there were on the reactant side, before the reaction.