Differentiating i= v/r (1-e^-Rt/L) to Find di/dt: Product Rule or Other Rule?

[Thepiman]

Homework Statement

i= v/r (1-e^-Rt/L)

How would i go about differentiating this formula to get di/dt? Would I use the product rule or another rule?

Homework Equations

i= v/r (1-e^-Rt/L)

The Attempt at a Solution

di/dt= ?

 

[6c 6f 76 65]

Open the parenthesis, then differentiate

 

[DrClaude]

You have many options. You can use the product rule or distribute the $v/r$ inside the parenthesis and derive the sum. If you make no mistake, the answer will be the same.

Go ahead, start solving and tell us what you get.

 

[Thepiman]

I got di/dt= R/L x e^-Rt/L

Using the chain rule.

 

[DrClaude]

I got di/dt= R/L x e^-Rt/L

Using the chain rule.

What happened to $v/r$?

 

[Thepiman]

Does it not cancel out?

 

[Mark44]

Homework Statement

i= v/r (1-e^-Rt/L)

How would i go about differentiating this formula to get di/dt? Would I use the product rule or another rule?

Homework Equations

i= v/r (1-e^-Rt/L)

The Attempt at a Solution

di/dt= ?

Does it not cancel out?

Are r and R different variables? I suspect from what you wrote that they aren't. If you mean them to be the same, then be consistent by not mixing upper and lower case letters. That is, don't use r and R interchangeably.

I got di/dt= R/L x e^-Rt/L

You have i = (V/R)(1 - e^(-Rt/L)) = (V/R) - (V/R)e^(-Rt/L)
Now differentiate with respect to t. The answer you got above is incorrect.