What Are the Main Characteristics of Ohmic and Non-Ohmic Conductors?
The topic "Difference Between Ohmic And Non Ohmic Conductors" is crucial in understanding electric circuits, as it helps students distinguish between materials that obey Ohm's Law and those that do not. Exam questions often require clear identification and application of these differences.
Definition of Ohmic Conductors
Ohmic conductors are materials that obey Ohm’s Law, which means the current flowing through them is directly proportional to the applied voltage at constant temperature. Metal wires are common examples of ohmic conductors used in circuits.
In ohmic conductors, the resistance remains constant regardless of the applied voltage or current within a given range. They are fundamental for understanding Ohm's Law And Resistance in electric circuits.
Definition of Non Ohmic Conductors
Non ohmic conductors are materials that do not obey Ohm's Law. In these materials, the relationship between current and voltage is non-linear, and resistance varies with the applied voltage or current.
Non ohmic conductors include semiconductor devices, diodes, and filament lamps, where resistance can depend on factors like temperature and voltage. These materials are essential in understanding practical aspects of Current Electricity and electronics.
Difference Table
| Ohmic Conductors | Non Ohmic Conductors |
|---|---|
| Obey Ohm’s Law strictly | Do not obey Ohm’s Law |
| Current is proportional to voltage | Current is not proportional to voltage |
| Constant resistance with applied voltage | Resistance changes with applied voltage |
| Linear V-I characteristic graph | Non-linear V-I characteristic graph |
| Examples include copper and aluminum wires | Examples include diodes and thermistors |
| Mostly metallic conductors | Mostly non-metallic or semi-conducting materials |
| Used in resistors and basic circuits | Used in electronic components |
| Temperature does not affect resistance significantly | Resistance varies significantly with temperature |
| Current remains uniform across the conductor | Current may vary at different points |
| Best for predictable current control | Used for variable current control |
| Show straight-line relationship in V-I plots | Show curves in V-I plots |
| Widely used in electrical wiring | Widely used in sensors and electronics |
| Material resistivity is independent of voltage | Material resistivity depends on voltage |
| Useful for theoretical calculations | Useful for practical applications |
| No significant energy loss due to changing resistance | Energy loss changes with resistance variation |
| High stability under varying voltages | Low stability under varying voltages |
| Rarely used for controlling current automatically | Often used in automatic control applications |
| Example: Metal resistors in meters | Example: Light-emitting diodes (LEDs) |
| Easily calculated by $R = V/I$ | $R = V/I$ not valid for calculation |
| Typical in academic circuit problems | Typical in real-world device design |
Key Differences
- Ohmic conductors obey Ohm’s Law always
- Non ohmic conductors have variable resistance values
- Ohmic V-I curve is always a straight line
- Non ohmic V-I curve is always non-linear
- Ohmic conductors are mainly metals
- Non ohmic conductors are semiconductors or special devices
Examples
A copper wire showing constant resistance under different voltages is an ohmic conductor. A semiconductor diode, where the current increases sharply after a threshold voltage, is a non ohmic conductor. Such cases are extensively discussed in Electrical Resistance.
Applications
- Ohmic conductors used in resistors for circuit control
- Non ohmic conductors used in electronic switches and sensors
- Ohmic wires used in household wiring
- Non ohmic devices used in temperature sensors and diodes
One-Line Summary
In simple words, Ohmic conductors maintain constant resistance and obey Ohm's Law, whereas non ohmic conductors have variable resistance and do not obey Ohm's Law.
FAQs on Understanding the Difference Between Ohmic and Non-Ohmic Conductors
1. What is the difference between Ohmic and Non-Ohmic conductors?
Ohmic conductors follow Ohm’s law, while Non-Ohmic conductors do not obey it.
Key differences:
- Ohmic conductors: Show a linear relationship between current and voltage (V ∝ I); resistance remains constant.
- Non-Ohmic conductors: Do not have a linear V-I relationship; resistance changes with voltage or current.
- Examples of Ohmic conductors: Copper, silver, most metals.
- Examples of Non-Ohmic conductors: Diodes, filament lamps, thermistors.
2. What are Ohmic conductors?
Ohmic conductors are materials that obey Ohm’s law, where the voltage across them is directly proportional to the current through them.
Features:
- Linear V-I graph
- Constant resistance over a range of voltages
- Most metals like copper and silver are Ohmic conductors
3. What is a Non-Ohmic conductor? Give examples.
Non-Ohmic conductors are materials that do not follow Ohm’s law, showing a non-linear relationship between voltage and current.
Examples include:
- Semiconductor diodes
- Filament lamps
- Thermistors
- Electrolytes
4. State Ohm’s law and explain its limitations.
Ohm’s law states that the current through a conductor is directly proportional to the voltage across it, provided the temperature remains constant.
Limitations:
- Not obeyed by Non-Ohmic conductors
- Valid mainly for metals with constant physical conditions
- Temperature and material composition can affect validity
5. Give two differences between Ohmic and Non-Ohmic conductors.
Ohmic and Non-Ohmic conductors differ in behavior towards Ohm’s law.
- Ohmic: Linear V-I relationship; constant resistance
- Non-Ohmic: Non-linear V-I curve; resistance varies with voltage or current
6. Why does a filament lamp act as a Non-Ohmic conductor?
A filament lamp acts as a Non-Ohmic conductor because its resistance increases with temperature, causing a non-linear V-I graph.
- Current and voltage are not proportional
- Resistance rises as filament heats up
7. Is a diode an Ohmic or a Non-Ohmic conductor? Explain your answer.
A diode is a Non-Ohmic conductor, as it allows current to flow easily in one direction and offers high resistance in the opposite direction, causing a non-linear V-I characteristic.
8. What type of V-I graph do Ohmic and Non-Ohmic conductors depict?
Ohmic conductors have a straight-line V-I graph, indicating constant resistance, while Non-Ohmic conductors show a curved V-I graph, indicating changing resistance.
9. What factors can make a conductor behave as a Non-Ohmic substance?
Factors like increasing temperature, impurities, or intense electric fields can make a conductor Non-Ohmic, affecting resistance and altering the current-voltage relationship.
10. List examples of Non-Ohmic conductors commonly found in electronic circuits.
Common Non-Ohmic conductors in electronics include:
- Diodes
- LEDs (Light Emitting Diodes)
- Thermistors
- Transistors
