
 The rate of change of velocity per unit time is called acceleration.
 The rate of change of velocity per unit time is called acceleration.
 Its SI unit is m/s².
 Its SI unit is m/s².

 
        
             
        
        
        
I think the correct answer would be that because electromagnets are powerful and can be turned off and on anytime. Electromagnet is a magnet in which the magnetic field is made by the electric current that is induced to the system.
        
                    
             
        
        
        
Answer:
a. dW = ∫pEsinθdθ  b. W = p.E
Explanation:
a. We know torque τ = p × E = pEsinθ where θ is the angle between p and E
Let the torque τ rotate the dipole by an amount dθ. So, the workdone dW = ∫τdθ = ∫pEsinθdθ 
b. So, the total work done is gotten by integrating from 90 to θ. So, 
W = ∫₉₀⁰dW 
= ∫₉₀⁰pEsinθdθ 
= pE∫₉₀⁰sinθdθ 
= pE(cosθ - cos90) 
=pEcosθ 
= p.E
 
        
             
        
        
        
Yes, it is diffusion !
Diffusion is the process in which gas, through random movement of particles, tends to fill up the whole volume of the container in which it is placed. So a similar process would lead the smoke, which is in form of gas (or light particles), to fill in the whole room in which it is contained. 
        
             
        
        
        
When you look at this, you might not be sure which way to divide ...
Should you divide  6 by 5  or  5 by 6 ?
Here's a case where you can use your units to decide.
The question wants to know the 'period'.  That's a length of time,
so the answer needs to have units of time.
If you divide 'cycles' be 'time', you'll get  'cycles/second'.
That's Hz.  It's frequency, not time.
If you divide 'time' by 'cycles', you'll get 'seconds/cycle'.
That's time, and it's exactly the definition of 'period'.
            Period  =  (6 seconds) / (5 cycles)
                         =    (6 / 5)  seconds/cycle
                         =     1.2  seconds