Current Flow

[Abbsdad]

Hi,

Could someone please help with the following:

A charge q(t)=50+t Coulombs (C) flows into an electric component. Find the current flow.

I'm not sure if I have all the relevant information.

Many thanks in advance.

 

[Ratchit]

Abbsdad,

Could someone please help with the following:

A charge q(t)=50+t Coulombs (C) flows into an electric component. Find the current flow.

I'm not sure if I have all the relevant information.

The instantaneous current (not current flow) is the derivative of the charge flow, q = 50+t, with respect to time. The derivative is 1, so the instantaneous current (not current flow) is 1 amp.

Ratch

 

[Abbsdad]

Hi Ratchit,

Thanks for the reply.

Would it be possible to explain how you got the 1 amp.

I think I may have been side tracked, by thinking the 50 in the equation was equal to Q=C x V.

Many thanks.

 

[Ratchit]

Abbsdad,

Would it be possible to explain how you got the 1 amp.

I already did. I took the derivative of the charge flow (50+t) with respect to time. That gives a value of 1 amp. Are you familiar with derivatives?

I think I may have been side tracked, by thinking the 50 in the equation was equal to Q=C x V.

50 is a constant, whose derivative is zero.

Ratch

 

[crutschow]

I think I may have been side tracked, by thinking the 50 in the equation was equal to Q=C x V.

I believe you are confusing the terms. This equation relates to charge on a capacitor. This C is capacitance in farads and Q is the charge. It is not the same as the charge C (coulombs) in your first equation.

 

[BrownOut]

Would it be possible to explain how you got the 1 amp.

Many thanks.

Look at it this way. Current is charge per unit time, and has units of coulumbs/seconds or, equivalently, amps. So, for the equation q(t)=50 + t, the only term on the right side that contributes to current is the second term. The first is just a constant. It shows that 50 coulumbs of charge was present in the component to start with, but the component is accumulating charge at the rate of "t" coulumbs per second. So, at t=1 second, the component accumulates 1 more coulumb of charge, at t=2 seconds, it accumulates 2 coulumbs, etc. One coulumb per second is 1 amp.