This work evaluates the suitability of the distorted wave method (where the initial state distorted wave is due to static potential of helium atom in the initial state (11S) and the final state distorted wave is generated by the average of the initial state static potential and final state (23S or 23P) static potential of helium atom), for 11S-23S and 11S-23P excitations of helium atom by electron impact since they occur through exchange when spin dependent interactions are neglected. The differential and total cross sections for these excitations have been calculated and compared with other available theoretical and experimental results.