img src not working with navbar bootstrap

My image does not appear, nor does the alt, I have tried different paths, but no luck.

    <nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="index.html">
      <img src="//assets/images/psa.png" alt="" width="30" height="24" class="d-inline-block align-top">
      psa
    </a>
  </div>