Does ohms law applicable for resistor diode transistor Justify?

Answer 1

Ohm's law is applicable in every case, including resistors, diodes, and transistors.

While the resistance is not constant, particularly with diodes and even more so with transistors, the law applies, but the dynamics of the situation must be taken into consideration.

Even under AC conditions with capacitors and inductors, ohm's law applies, except that now resistance becomes more complex, becoming "impedance" and incorporating reactance, but it still applies so long as you consider every factor.

ANOTHER ANSWER

Ohm's Law does NOT apply to diodes or transistors.

Ohm's Law is a law of constant proportionality. It ONLY applies to those conductors and other components (such as diodes, transistors, etc.) whose ratio of voltage to current remains constant for variations in voltage. It does not apply to conductors or components whose ratio of voltage to current changes for variations in voltage. So Ohm's Law is not a universal law.

Conductors and other devices which obey Ohm's Law are termed 'linear' or 'ohmic'; those that do not (the majority, in fact!) are termed 'non-linear' or 'non-ohmic'. Some, but not all metals, are linear (e.g. tungsten is not) and most electronic components such as diodes, electrolytes, and gases are non-linear.

The ratio of voltage to current is, of course, resistance. And we can use this ratio to determine what the resistance of a device happens to be for that particular ratio, at any given voltage, even for devices that do not obey Ohm's Law. For non-linear devices, the ratio continuously changes for variations in voltage.

So, it's questionably whether Ohm's Law should be 'law' at all, and one might wonder why we even bother to teach it!

It is quite incorrect to define Ohm's Law as, "resistance equals voltage divided by current", as this equation is derived from the definition of the ohm, and NOT from Ohm's Law -which makes absolutely no reference to resistance.