Are these definitions correct?
Voltage/V the amount of energy to push charge around the circuit, Voltmeters measure the amount of energy used in a particular section/point of a circuit.
Capacitance is the ability of a capacitator to store energy in an electric field. (Farad/F)
Current is the amount of charge flowing around a circuit every second (measured in amps).
Period of a Wave is the time taken for a particle to make one complete cycle (measured usually in seconds).
Frequency (measured in Hertz/Hz)are the number of oscillations or waves in a period of time, usually in seconds.
Wavelength is the distance between sucessive crests/troughs for transverse waves, and successive compressions/rarefractions for londitudinal waves and is measured in metres.
Your definitions are essentially correct. I offer the following suggestions for clarification:
Voltage: The amount of energy pushing electrons around a circuit. Voltage is also called potential difference, and is likened to pressure.
Capacitance: The ability to allow current flow in proportion to the rate of voltage change. Capacitors charge and discharge, allowing maximal current when voltage changes are highest. Capacitance is expressed as Farads. It is the ability to store a charge.
Current: No suggestions.
Period of a wave: The time between two equivalent points on the wave (for example crests or troughs), usually expressed in seconds.
Frequency: Number of wave cycles per second, expressed as Hertz.
Wave length: No suggestions.
Yes. They are correct.