As the technology is advancing, humans are being exposed to devices that emit radiation. Cell phone is one such device that people use almost every day. Because of this radiation, we observe various health issues like severe headache, tumors etc. The human tissues undergo changes due to this radiation. These changes have to be monitored to avoid such diseases. In this paper, we have done a comparative study between brain and brain tumor based on the variations in Specific Absorption Rate (SAR) and temperature rise at a frequency of 835 MHz due to radiation. A multiphysics model has been designed and subjected to radiation using a patch antenna as RF source, the effects have been studied.