This is a compilation of four dissertations based on experimental projects presented to Vidyasagar University by four final year undergraduate students of Jhargram Raj College, Jhargram-721507, West Bengal, India, under my supervision. The topics were selected while I was giving instructions on laboratory work to undergraduate students there. The subjects embody a detailed idea of OPAMP in electronics, its different applications, some new experiments based on OPAMP, which yield qualitative and quantitative information about OPAMP. The second chapter is based on the idea of OPAMP. The third chapter is based on the characteristics of differential amplifier, logarithmic amplifier, and antilogarithmic amplifier mode of OPAMP. Exhaustive studies on measuring the thermo-emf of a thermo couple with two and one junction using inverting amplifier mode of OPAMP is given in chapter four. Finally in the fifth chapter a dissertation on the measurement of the variation of Zener breakdown voltage with temperature using differential amplifier mode of OPAMP is given.