Why Can't Ohm's Law Be Applied Here?

In summary, we are given the equation I = Io (exp (V/Vo) -1) and asked to find R for two different values of V, plot the graph of V vs I, and explain why Ohm's law cannot be applied. Using the given values of Io = 1 A and Vo = 1 V, we find that R is equal to 5/[(e^5) - 1] ohm when V = 5 Volt and 10/[(e^10) - 1] ohm when V = 10 Volt. The graph of V vs I will be an exponential curve, similar to y = e^x. Ohm's law cannot be applied in this case because
  • #1
songoku
2,326
331

Homework Statement


Given I = Io (exp (V/Vo) -1), Io = 1 A, Vo = 1 V, R = 1 ohm
(i) Find R when V = 5 Volt
(ii) Find R when V = 10 Volt
(iii) Plot the graph of V vs I
(iv) Explain why the Ohm’s law can’t be applied



Homework Equations


V = I*R


The Attempt at a Solution


(i) Subs. to the equation given, i got I = (e^5 ) - 1. Then R = V / I = 5 / [(e^5 ) - 1] ohm

(ii) Use the same method as (i), I got R = 10 / [(e^10 ) - 1] ohm

I'm not sure I can use V=I*R, but I don't know the other way to find R


(iii) the graph will be exponential curve similar to y = e^x

(iv) The Ohm's law can't be applied because the relation between V and I is not linear.


Do I get it right?

Thanks
 
Physics news on Phys.org
  • #2
Even in a non-ohmic circuit, you can the ohm's law at a particular instant.
 
  • #3
Hi Mr. rl.bhat

Ok then I think my answers are right. Thanks
 

Related to Why Can't Ohm's Law Be Applied Here?

1. Why can't Ohm's law be applied in all situations?

Ohm's law states that the current flowing through a conductor is directly proportional to the voltage and inversely proportional to the resistance. However, this law only applies to ohmic materials, meaning materials that have a constant resistance regardless of the applied voltage. In other situations, such as with non-ohmic materials or in circuits with changing conditions, Ohm's law may not be accurate.

2. What are some examples of situations where Ohm's law cannot be applied?

One example is in circuits with components that have non-linear voltage-current relationships, such as diodes or transistors. In these cases, the resistance of the component changes with the voltage, making Ohm's law invalid. Another example is in high-frequency circuits, where the reactance of capacitors and inductors also affects the current flow.

3. Can Ohm's law be applied to AC circuits?

Yes, Ohm's law can be applied to AC circuits, but with some modifications. In AC circuits, the voltage and current are constantly changing, so the values used in Ohm's law calculations should be the root mean square (RMS) values instead of the peak values. Additionally, the concept of impedance, which takes into account the effects of capacitance and inductance, is used instead of resistance.

4. Why is it important to understand when Ohm's law can't be applied?

Understanding when Ohm's law cannot be applied is crucial for accurately analyzing and designing electrical circuits. Trying to apply Ohm's law in situations where it is not valid can lead to incorrect calculations and potentially dangerous situations. It is important to have a solid understanding of the limitations of Ohm's law to ensure the safety and functionality of electrical systems.

5. How can I determine if Ohm's law can be applied in a specific circuit?

To determine if Ohm's law can be applied in a specific circuit, you need to consider the properties of the materials and components used in the circuit. If all the materials are ohmic and the circuit conditions are not changing, then Ohm's law can be applied. However, if there are non-ohmic materials or changing conditions, then Ohm's law may not be applicable.

Similar threads

Ohm's Law - Finding Source Voltage
    • Introductory Physics Homework Help
Replies
3
Views
764
Ohm's law, current density, free & bound charge
    • Introductory Physics Homework Help
Replies
16
Views
1K
Ohm's law and Kirchoff — What am I missing?
    • Introductory Physics Homework Help
Replies
4
Views
1K
Long distance electrical transmission efficiency
    • Introductory Physics Homework Help
Replies
2
Views
1K
How to solve for EMF and internal resistance in a circuit?
    • Introductory Physics Homework Help
Replies
8
Views
2K
Calculate the magnetic moment of a rotating sphere
    • Introductory Physics Homework Help
Replies
17
Views
655
Understanding the math of definition of electromotive force
    • Introductory Physics Homework Help
Replies
1
Views
348
Connection between V vs I graphs and Ohm's Law
    • Introductory Physics Homework Help
Replies
7
Views
5K
Using Current and Voltage Dividers
    • Introductory Physics Homework Help
Replies
3
Views
885
Determine the effective current value in the circuit with C and R
    • Introductory Physics Homework Help
Replies
3
Views
963

Hot Threads

Recent Insights

Back
Top