Derivative of current and voltage

Click For Summary

Discussion Overview

The discussion revolves around the derivatives of current and voltage with respect to time, exploring whether these derivatives correspond to any specific physical quantities. The scope includes theoretical considerations and relationships in electrical circuits, particularly in the context of inductors and capacitors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that in an inductor, the relationship dI/dt = V/L holds, and in a capacitor, dV/dt = I/C, suggesting specific physical interpretations of these derivatives.
  • Others argue that the question lacks meaning without specifying conditions, as current and voltage are dependent on circuit behavior, implying that derivatives can only be taken once equations are established.
  • A participant raises the concept of "physical quantities," mentioning that the first derivative of charge with respect to time results in current, and questions whether the second derivative yields another physical quantity.
  • Another participant discusses the translation of "grandeza física" and lists various physical quantities, indicating a broader context for understanding derivatives in physics.

Areas of Agreement / Disagreement

Participants express differing views on the meaningfulness of the original question, with some providing specific relationships while others emphasize the need for context and equations. The discussion remains unresolved regarding the general applicability of derivatives of current and voltage.

Contextual Notes

The discussion highlights limitations in assumptions about circuit conditions and the need for specific equations to derive meaningful relationships. There is also ambiguity regarding the interpretation of "physical quantity" in the context of derivatives.

Jhenrique
Messages
676
Reaction score
4
Exist some physical quantity for the derivative of the current wrt time? Exist another too for the derivative of the voltage wrt time?
 
Physics news on Phys.org
Jhenrique said:
Exist some physical quantity for the derivative of the current wrt time? Exist another too for the derivative of the voltage wrt time?

In an inductor dI/dt = V/L and in a capacitor dV/dt = I/C
 
Jhenrique said:
Exist some physical quantity for the derivative of the current wrt time? Exist another too for the derivative of the voltage wrt time?

This is a meaningless question. Current is a function of what is happening in the circuit and so is voltage. You have to find the equations for the current and voltage and then, sure, you can take the derivative. You have not specified any conditions, so there is nothing to take a derivative OF.

As Jhenrique pointed out, for the very limited cases of an inductor and a capacitor there are specific relationships among voltage/current/inductance and voltage/current/capacitance
 
I don't know how the americans speak "grandeza física" (pt-br) in english. "Grandeza física" for me is: area A, volume V, voltage v, force F, work W, power P, velocity v, acceleration a, etc, etc. I think that the translate is "physical quantity". Anyway... the first derivative of the carge q(t) wrt time t results the current i(t), so, the 2nd derivative results another "physical quantity" ?(t) ?

Similarly, dΦ/dt = v(t), so d²Φ/dt² = ?(t)
 

Similar threads

Undergrad Are voltage and current waves in transmission lines an artifice?
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad Which law defines the AC inducing voltage in the inductor?
  • · Replies 25 ·
Replies
25
Views
3K
Undergrad Current's Effect on Electrical Arcs
  • · Replies 9 ·
Replies
9
Views
4K
High School Voltage & Current: Explaining the Basics for Beginners
  • · Replies 11 ·
Replies
11
Views
2K
High School Found a circuit where current is zero across an ohmic device (dV>0)
  • · Replies 11 ·
Replies
11
Views
1K
High School Phase Difference of Current & Voltage: Capacitors, Inductors & Complex Numbers
  • · Replies 8 ·
Replies
8
Views
2K
Undergrad Can I Apply Voltage to Non-Conducting Plates?
  • · Replies 15 ·
Replies
15
Views
2K
Undergrad Question about Capacitor current and electromagnetic induction
  • · Replies 16 ·
Replies
16
Views
2K
Undergrad Does current decrease inside a wire or does it increase it's velocity?
  • · Replies 8 ·
Replies
8
Views
2K
Undergrad Electrical characteristics of a solenoid coil
  • · Replies 10 ·
Replies
10
Views
2K