What is the difference between active and passive elements ?

Active Components:Those devices or components which produce energy in the form of Voltage or Current are called as Active ComponentsFor Example: Diodes Transistors SCR etc…   Passive Components:Those devices or components which store or maintain Energy in the form of Voltage or Current are known as Passive ComponentsFor Example:  Resistor, Capacitor, Inductor etc…   In very Simple words;Active Components: Energy DonorPassive Components: Energy AcceptorAlso Passive Components are in linear and Active Components are in non linear category.

Components which requires energy/power for their operation is called Active components ,

Components which did not exterbal energy/power for their operation is called passive coponents

Active Components:Those devices or components which produce energy in the form of Voltage or Current are called as Active ComponentsFor Example: Diodes Transistors SCR etc…  Passive Components:Those devices or components which store or maintain Energy in the form of Voltage or Current are known as Passive ComponentsFor Example:  Resistor, Capacitor, Inductor etc…

An active Element is one which requires a controla signal / biasing in addition to the input  to control the out put - Tansistors , thyristors , etc.

While those elements like resistors , capcitors and inducturs are considered to be passive elements 

Active Elements= Supply energy in the form of voltage or current.

Passive Elements: Store or dissipate energy.

ANY SOILD STATE DEVICE WORKING WITH POWER SUPPLIES IS ACTIVE.

AND WITHOUT POWER SUPPLY IS PASSIVE

Active components requires external power supply while passive is not.

Active Components:Those devices or components which required external source to their operation is called Active Components. like-diode, transistor ,SCR

hose devices or components which do not required external source to their operation is called Passive Components.like- Resistor, Capacitor, Inductor

 

A detail answer is already added by Mr Adnan Ahmad

In the PLC world, the difference between Active and Passive elements its related to Analogic Inputs (AI), and specifically related to the way you wired those instruments to the PLC Analogic Input Module. On a active element the Power Supply of the instrument its external to the PLC, on a passive element the Power Supply its the PLC Power Supply connected via the signal wires.

Still concerning AI you also should look for the diference between Commun Ground and Diferencial AI.