(a) semiconductors
(b) vacuum tubes
(c) electrolytes
(d) carbon resistors
(e) arc lamps
(f) none of these
Correct Answer: (f) none
of these
Explanation
All listed devices show
non-linear V–I characteristics.
Notes for
More Information
Ohm’s Law
- Ohm’s law states that at constant
temperature, the current flowing through a conductor
is directly proportional to the voltage applied
across it.
- Mathematically,
Ohm’s law is written as:
- Where:
- V = Voltage
- I = Current
- R = Resistance
- The SI
unit of resistance is the ohm (Ω).
- Ohm’s
law is useful for calculating:
- Current
- Voltage
- Resistance
- Power
- Efficiency
of an electrical circuit element.
Limitations of Ohm’s Law
- Ohm’s
law is not applicable to unilateral networks.
- Unilateral networks allow current to flow only
in one direction.
- Examples
of unilateral elements are:
- Diode
- Transistor
- Ohm’s law is not applicable to
non-linear elements.
- Non-linear elements are those in which current is not exactly
proportional to the applied voltage.
- In such elements, the resistance
changes with different values of voltage and current.
- An example of a non-linear element is a thyristor.
- Ohm’s law is also not applicable to
vacuum tubes.
- In vacuum tubes, current flow does not follow
a linear V–I relationship.
Key Takeaway
- Ohm’s
law is valid only for linear, bilateral conductors at constant
temperature.
- It
does not apply to devices where the V–I
relationship is non-linear or direction-dependent.
