An equivalent single current source between 'A' and 'B' in the following figure will be: 

Concept:

• Norton’s Theorem states that “Any linear circuit containing several energy sources and resistances can be replaced by a single constant current source in parallel with a single resistor".
• It is an analytical method used to change a complex circuit into a simple equivalent circuit consisting of a single resistance in parallel with a current source.

Steps to follow for Norton’s Theorem:

• Calculate Norton’s current source by removing the load resistor from the original circuit and replacing it with a short circuit.
• Calculating the current through a shorted wire.
• Calculating the Norton resistance by removing all power sources in the original circuit (voltage sources shorted and current sources open).
• Calculating total resistance between the open connection points.
• Draw the Norton equivalent circuit, with the Norton current source in parallel with the Norton resistance.
• The load resistor re-attaches between the two open points of the equivalent circuit.

Calculation of Norton Resistance

Step 1: Open the load terminal AB.

Step 2: Short circuit the voltage source and open circuit the current source.

R_N = 10Ω 

Calculation of Norton's Current

Short circuit the load terminal. This short circuit current is known as the Norton current.

\(-5-10+10I+5=0\)

I = 1A

Applying KCL at Node B:

I_B = 1+1 = 2A = I_N