Self-inductance is the property of a circuit whereby a change in current causes a change in voltage.  

where: 

V_L = the induced voltage in  volts, V  
L = the value of self-inductance in henries, H  
di / dt = the rate of change in current in amperes per second, A/T

• When there is no change in current, di /dt = 0 and V_L = 0.
• When the current is changing very rapidly, di/dt is a large value and so is the amount of V_L.
• When the current is changing very slowly, di/dt is a small value and so is the amount of V_L.

Self-inductance is also more simply known as inductance. 

The self-induction effect is multiplied by the value of inductance, L.  

• Increasing the value of L increases the amount of voltage that is induced in response to a change in current.
• Decreasing the value of L decreases the amount of voltage that is induced in response to a change in current.

Inductance is measured in units of Henries (H).  

The math symbol for inductance is L.  

The graphical symbol for an inductor resembles a coil of wire:  

Commonly used engineering units for inductance are:  

• 1 H = 1 henry
• 1 x 10^-3 H = 1 mH or millihenry
• 1 x 10^-6 H = 1 mH or microhenry

One henry is the amount of inductance that is required for generating one volt of induced voltage when the current is changing at the rate of one ampere per second.  

V_L = 1 V when L = 1 H and di /dt = 1 A / sec 

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• The amount of induced voltage is proportional to the rate of change of current through an inductor.
• The value of a sine waveform is constantly changing.
• Therefore, when a sinusoidal current flows through an inductor (I_L), the induced voltage (V_L) changes constantly.