A transformer. it steps up / down voltage, and steps down / up current.
A variable resistor.
A Transformer.
current transformer (CT)
Rheostat.
The ratio of output windings to input windings determines the ratio of output voltage to input voltage. The ratio of current is the inverse.
Current gain is the ratio of output current divided by input current. Voltage gain is the ratio of output voltage divided by input voltage. Nothing more complicated than that.
Absolutely not! A tungsten filament is an example of a non-linear or non-ohmic material, and it does not obey Ohm's Law. Ohm's Law is a law of constant proportionality; in other words, for it to apply, the ratio of voltage to current must be constant over a wide range of voltages. Increasing the voltage of a tungsten filament to its rated voltage causes its resistance to increase around 15 - 18 times, compared with its 'cold' resistance. Therefore, the ratio of voltage to current changes significantly as the applied voltage changes -so it does not obey Ohm's Law.However, the ratio of voltage to current will always tell you what the resistance happens to be for any particular ratio. Since, for tungsten, because the ratio increases as the voltage increase, the resistance changes too.To summarise, for Ohm's Law to apply, there MUST be a linear relationship between voltage and current; with tungsten, the relationship is a curved line and, so, it is non-linear and does not obey Ohm's Law.
It's approximately the inverse of the voltage- or turns-ratio:
it defines the voltage and current ratio.
A transformer. it steps up / down voltage, and steps down / up current.
A rectifier is a device that converts alternating current to direct current. A transformer is a device that changes the ratio fo current to voltage. A rectifier is found in a PC power supply.
V = I * RThe equation you are looking for is R = V/I, although this is derived from the definition of the ohm, not Ohm's Law!Ohm's Law is merely a statement which, in effect, says that for a limited range of conductors, the ratio of voltage to current is constant for variations in voltage.If the ratio of voltage to current changes for variations in voltage, then Ohm's Law does not apply.However, the ratio of voltage to current will always tell you what the resistance of a load or device happens to be for that particular ratio.
If the ratio of voltage to current is constant, then the circuit is obeying Ohm's Law. If the ratio changes for variations in voltage, then the circuit does not obey Ohm's Law.
The ratio of output windings to input windings determines the ratio of output voltage to input voltage. The ratio of current is the inverse.
It's an immutable law of physics! It applies to a.c. too but only if the circuit is purely resistive.AnswerOhm's Law is not a universal law, and only applies to a limited range of conductors or loads, called 'linear' or 'ohmic' conductors or loads. Basically, it only applies when the ratio of voltage to current is constant for variations in applied voltage. If this ratio changes for variations in voltage, then the conductor (e.g. tungsten) or load (e.g. diode) does NOT obey Ohm's Law and is termed 'non-linear' or 'non-ohmic'.The ratio of voltage to current is called 'resistance', and the ratio will ALWAYS tell you what the resistance happens to be for that particular ratio (if the ratio varies with voltage, then so too does the resistance), whether the conductor/device obeys Ohm's Law or not!So Ohm's Law really has nothing to do with a circuit having a 'steady current'; it's all to do with whether or not the ratio of the circuit's voltage to current is constant for variations in voltage. Nothing more!
Current gain is the ratio of output current divided by input current. Voltage gain is the ratio of output voltage divided by input voltage. Nothing more complicated than that.
because current is the ratio of voltage and resistance.
voltage to current ratio is called resistance. it is d opposition offered to d flow of charges.........
Absolutely not! A tungsten filament is an example of a non-linear or non-ohmic material, and it does not obey Ohm's Law. Ohm's Law is a law of constant proportionality; in other words, for it to apply, the ratio of voltage to current must be constant over a wide range of voltages. Increasing the voltage of a tungsten filament to its rated voltage causes its resistance to increase around 15 - 18 times, compared with its 'cold' resistance. Therefore, the ratio of voltage to current changes significantly as the applied voltage changes -so it does not obey Ohm's Law.However, the ratio of voltage to current will always tell you what the resistance happens to be for any particular ratio. Since, for tungsten, because the ratio increases as the voltage increase, the resistance changes too.To summarise, for Ohm's Law to apply, there MUST be a linear relationship between voltage and current; with tungsten, the relationship is a curved line and, so, it is non-linear and does not obey Ohm's Law.
Yes
Under normal circumstances, the relationship is given by Ohm's lawvoltage = current x resistance.The ratio of voltage to current is called resistance. This is obtained from the definition of the ohm, and not (as so often stated) from Ohm's Law.If the ratio of voltage to current is constant for variations in voltage, then the load obeys Ohm's Law and is called a 'linear' or 'ohmic' load.If the ratio of voltage to current changes for variations in voltage, then the load does NOT obey Ohm's Law, and is called 'non-linear' or 'non-ohmic'. Pure metal conductors ONLY obey Ohm's Law if their temperature is held constant. No semiconductor obeys Ohm's Law.