How to calculate the time over which flux changes

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To calculate the time over which magnetic flux changes in a 50-turn coil, the formula E = -N (change in flux / change in time) is used. Given a change in flux from 10 mWB to 20 mWB and an induced e.m.f. of 62.5 V, the calculation leads to a negative time value, which is not physically meaningful. The negative sign can be disregarded since e.m.f. is typically expressed as an absolute value. The calculated time for the flux change is 0.008 seconds. Understanding the polarity of e.m.f. is crucial for accurate calculations.
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1. if the magnetic flux linking all the turns of a 50 turn coil changes from 10 mWB to 20 mWB and induces an e.m.f. of 62.5 V in the coil, calculate the time over which the flux changes.

i know the formula to calculate the flux which is

E = -N change in flux / change in time.

to calculate the change in time we just need to change E with change in time in the formula, but by doing this answer will be negative which is not possible as time can not be negative. how to get rid of this -ve. or is it ok if i don't use it at all.


my answer is -0.008 Sec.



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The 62.5V polarity was not defined with respect to coil geometry so your answer is correct when made positive.
 
62.5 V is an absolute value of e.m.f
 
thnx a lot guyz... :D
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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