All that is required to analyze any electronic circuit is a thorough understanding of three laws, Ohm's Law, Kirchhoff's Voltage Law and Kirchhoff's Current Law. However, before these laws can be mastered, the student needs to understand the basic units of electricity (voltage and current) and the concept of resistance.
Read from here
http://cktse.eie.polyu.edu.hk/eie209/1.CircuitAnalysis.pdf
Read from here
http://cktse.eie.polyu.edu.hk/eie209/1.CircuitAnalysis.pdf