A transformer can only increase or decrease
the voltage of an alternating current, and it is called step-up transformer or step-down transformer accordingly.
The device you are referring to is called a transformer. Not only can a transformer increase voltage, it can decrease voltage as well. These are known as a step up transformer for increasing voltages and step down for decreasing voltages.
Because it is only possible to have a voltage in the secondary winding when the current in the primary is changing. This is why only alternating current can be used for transformers.
because there is no transformer to step up or step down the dc voltage,and in the world most of the components are manufactured in the usage of ac only , that is the reasoning for usage of alternating current
Voltage Tarnsformer transforms only voltage. While power transformer transforms both voltage and current.
Induction occurs only with alternating current.
No, a transformer does not change AC to DC. For this purpose there is a device known as a rectifier, and to transform it back to AC from DC you'll need an inverter. Transformers are only useful with AC due to the alternating waveform which induces a voltage in the secondary winding (when it is connected to a load).
DC current cannot be used in a transformer only AC will work. A transformer needs the continual build and collapse of the magnetic field to keep the iron core from reaching saturation. Only alternating current will transfer power through a transformer.
There is no positive and negative on a transformer. Transformers will only pass AC (alternating current), due to the fact that induction will only occur with a moving field. The current has to be changing polarity and intensity continuosly, for the current to be induced in the windings. Both terminals on the output vary, with relation to each other. Put DC into a transformer and the coils will saturate, overheat and probably burn out.
In a DC power supply a transformer is connected. The only time there would be no transformer used would be if the DC voltage wanted was 120 VDC. The transformer in the power supply is connected to 120 VAC on the primary side and the secondary side of the transformer is connected to either a half wave or a full wave diode bridge. The voltage out of the diode bridge will be the same output voltage potential as the transformer's secondary voltage but it will be a DC (Direct Current) potential.Reading the question in another way, transformers are not connected in a DC circuit. The reason being is that the transformer operates on a collapsing magnetic field. This field induces a voltage into the secondary side of the transformer. Since the DC circuit does not operate on the principle of a collapsing field except when the circuit is opened, the transformer would not operate as a transformer should..
Frequency does not change when you use a step-up or step-down transformer. Only current and voltage is changed.
Perhaps you are asking how the voltage of alternating current is measured, to be equivalent to the voltage of a direct current system. Alternating current and direct current have distinct properties. With direct current, voltage is at a constant polarity, and a direct current voltage source will maintain a uniform, constant voltage level. Alternating current reverses polarity at a given frequency and therefore it's voltage continuously varies from a positive peak voltage level, through zero, to a negative peak voltage level, repeating this cycle continuously. For this reason, voltage of an alternating current system, is measured in root-mean-square (rms), which is a voltage, which when multiplied by the current in amperes, calculates power which is equivalent to that of direct current of the same voltage and current values. With a typical sinusoidal waveform, the peak voltage of alternating current is divided by the square root of 2 to determine the rms voltage. The 120 volts output in the wall outlet in our home is actually about 170 peak volts.
In DC, flow of current is controlled by resistance only where as in AC it is done by Impedance which is combination of Resistance , inductive and capacitive reactances.Reasons:In transformers resistance of the transformer's core windings are very low due to which if you will connect transformer across DC supply then it will draw a heavy current which will burn out is winding and it may damage the equipment too.Transformers works of the principal of Induction (Mutual/Self) that is possible in AC only because in DC there is no induction therefore even if transformer's windings anyhow withstand with DC there will be no voltage output at output terminals of the transformer, therefore it is useless to connect transformer on DC supply.