Dear smita,
The cover letter you choose for transmitting your resume to an employer or important networking contact can be one of the most significant factors in the success (or failure) of your job-hunting campaign.
If well written and informative, the cover letter can grab the reader's attention, raise his curiosity, and stimulate immediate interest in your employment candidacy. In fact, if particularly well written, it can sometimes raise sufficient interest to compel the reader to extend an interview invitation without reading the resume document to which it is attached.
Kindly find the sample cover letter.