AIP Conference Proceedings [AIP Publishing THE 1ST INTERNATIONAL CONFERENCE ON PHYSICS AND APPLIED PHYSICS (THE 1ST ICP&AP) 2019: Fundamental and Innovative Research for Improving Competitive Dignified Nation and Industrial Revolution 4.0 - Medan, Indonesia (12–13 September 2019)] THE 1ST INTERNATIONAL CONFERENCE ON PHYSICS AND APPLIED PHYSICS (THE 1ST ICP&AP) 2019: Fundamental and Innovative Research for Improving Competitive Dignified Nation and Industrial Revolution 4.0 - Study on the effect of CaO addition on micro structure and magnetic properties of BaFe12O19 made using powder metallurgy technique