Electric charge (positive and negative) is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.

Voltage is an electromotive force or potential difference expressed in volts.

Electric current is a flow of electric charge.

Electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor.

Ohm's Law deals with the relationship between voltage and current in an ideal conductor (V = I R). 

Power is the rate of doing work, amount of energy consumed per unit time. 

Direct Current is an electric current flowing in one direction only.

Alternating current is an electric current that reverses its direction many times a second at regular intervals, typically used in power supplies.

Frequency is the number of occurrences of a repeating event per unit time. 

Period T is the time needed for one complete cycle of vibration to pass a given point.

Peak-to-peak voltage, VPP, is a voltage waveform which is measured from the top of the waveform, called the crest, all the way down to the bottom of the waveform, called the trough.

Peak voltage, VP, is a voltage waveform which is measured from the horizontal axis (at the 0 height reference mark) to the top of the waveform, called the crest of the waveform.

Average voltage is the quotient of the area under the waveform with respect to time.

Explain the structure of atom