Negative sign in voltage equation

In summary, the resistance equation in Ohm's Law ignores the negative sign because the voltage refers to the potential drop, which is negative. The current flows in the direction of the electric field, while the potential decreases in the opposite direction.
  • #1
baby_1
159
15
hello
as we know if we wanta find the resistance of a material we use this equation
%7D.%5Cvec%7Bdl%7D%29%7D%7B%5Cint%20%5Cint%20%28%5Csigma%5Cvec%7BE%7D.%5Cvec%7Bds%7D%29%20%29%7D.gif

but in electromagnetic course we know that voltage equation has negative sign that it is refer to positive charge thas positive sing and negative charge has negative sing .
gif.latex?V_%7Bab%7D%3D-%5Cint_%7Bb%7D%5E%7Ba%7D%28%5Cvec%7BE%7D.%5Cvec%7Bdl%7D%29.gif

why in resistance equation we ignore negative sign?
 
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  • #2
baby_1 said:
hello
as we know if we wanta find the resistance of a material we use this equation
%7D.%5Cvec%7Bdl%7D%29%7D%7B%5Cint%20%5Cint%20%28%5Csigma%5Cvec%7BE%7D.%5Cvec%7Bds%7D%29%20%29%7D.gif

but in electromagnetic course we know that voltage equation has negative sign that it is refer to positive charge thas positive sing and negative charge has negative sing .
gif.latex?V_%7Bab%7D%3D-%5Cint_%7Bb%7D%5E%7Ba%7D%28%5Cvec%7BE%7D.%5Cvec%7Bdl%7D%29.gif

why in resistance equation we ignore negative sign?

The voltage in Ohm's Law means potential drop, negative potential difference. The potential decreases in the direction of the electric field, and the current flows in the direction of the electric field.

ehild
 
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FAQ: Negative sign in voltage equation

1. What does a negative sign in a voltage equation mean?

The negative sign in a voltage equation indicates the direction of current flow. A negative voltage means that current is flowing in the opposite direction of a positive voltage.

2. Can a voltage be negative?

Yes, a voltage can be negative. This means that the electron flow is in the opposite direction compared to a positive voltage.

3. How do you interpret a negative voltage value?

A negative voltage value means that the current is flowing in the opposite direction compared to a positive voltage. This is typically represented by an arrow pointing in the opposite direction in a circuit diagram.

4. What is the relationship between voltage and current in a negative voltage equation?

In a negative voltage equation, the current and voltage have an inverse relationship. This means that as the voltage decreases, the current increases and vice versa.

5. Why do we use negative voltages in electrical circuits?

Negative voltages are used in electrical circuits to represent the direction of current flow. They also play a crucial role in understanding the behavior of components such as diodes and transistors.

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