About a month ago, i studied Ohm's law which said voltage is directly proportional to electric current. But today when i was studying about transformer, it said that if number of turns of the secondary coil is more than that of primary, then the induced voltage is higher than the primary voltage which was supplied and the current throught the secondary coil is less. How can this be? If voltage increases, current should also increase right? And what is the difference between emf and current?
Ohms Law relates how current through a resistance varies with the voltage applied across that resistance, via the formula IV/R (or V IR). Transformers are not resistances. They are devices that transform one voltage and current level to another voltage and current level without increasing or decreasing the amount of power that is transformed. In that respect they don't follow ohms law. The amount of current that you have to input into a transformer depends upon how much load is connected to its output. If instead the transformer were a resistor, the current would depend solely upon the applied voltage. Not true for a transformer. So for a transformer rated 1000VA (volt-amps), with a 10V primary (input) and a 100V secondary (output), the rated primary current with a full load connected would be: 1000VA / 10V 100A The rated secondary current with a full load connected would be: 1000VA / 100V 10A For a lesser connected load, both of the above calculated currents would decrease. What does rated current mean? It means the transformer is rated to handle that much current (it is a maximum rating) without overheating and without distorting the output waveform significantly.
Power stays constant on both sides. As P U*I, that means if one of either voltage or current increases, the other one must decrease. emf is basically voltage. The U R*I is also valid, but if the two coils have different number of turns, they also have different R values.
The product of voltage and current should be equal,both in input and output less conversions loss.
Ohm's regulation, the place it applies, will consistently artwork. the significant factor is the place it applies. on your case, the present is decreased via a million/20 interior the secondary whilst in comparison with the present interior the regularly occurring. however the fee of the secondary present day might nicely be calculated via making use of ohms regulation in case you have a resistor load. case in point, in case you have a one hundred volts utilized to the regularly occurring, then the secondary is 2000 volts. in case you have a a million M? load, the secondary present day is 2000/1M 2 mA. meaning the regularly occurring present day is 20 x 2mA 4 hundred mA. in case you alter the burden to 100k?, then the secondary present day is 20 mA and the regularly occurring present day is 4 amps.
