How do I display an index below a variable?

[e2bady (Sebastian van Wickern)]

I want to display a lower index within my wolframalpha results (like you see within the attached image, the l_B), since I’m not sure how to call this in english I have a hard time searching for the correct syntax in the documentation. I tried the common notations (l_B, l_{B}, l[B], l{B},..) but I couldn’t get it to work. Does anyone know how the syntax for this is?

Just to be clear, I want to display the B like in the attached png.

Thanks for your help!

[seanc (Sean Clarke)]

Wolfram|Alpha, as far as I know, doesn’t produce output with subscripts.

You can use Mathematica or Mathematica Online to do this however. The expression is Subscript:

Subscript: Place a character below the baseline—Wolfram Documentation