diff --git a/docs/source/input.rst b/docs/source/input.rst
index 457661cc..20309f67 100644
--- a/docs/source/input.rst
+++ b/docs/source/input.rst
@@ -638,8 +638,8 @@ Allows you to specify waveforms to use with sources in the model. The syntax of
     * ``ricker`` which is a Ricker (or Mexican hat) waveform, i.e. the negative, normalised second derivative of a Gaussian waveform.
     * ``sine`` which is a single cycle of a sine waveform.
     * ``contsine`` which is a continuous sine waveform. In order to avoid introducing noise into the calculation the amplitude of the waveform is modulated for the first cycle of the sine wave (ramp excitation).
-* ``f1`` is the amplitude of the waveform.
-* ``f2`` is the frequency of the waveform in Hertz.
+* ``f1`` is the amplitude of the waveform (for a ``#hertzian_dipole`` the units will be Amps, for a ``#voltage_source`` or ``#transmission_line`` the units will be Volts).
+* ``f2`` is the frequency of the waveform (Hertz).
 * ``str2`` is an identifier for the waveform used to assign it to a source.
 
 For example, to specify a Gaussian waveform with an amplitude of one and a centre frequency of 1.2 GHz, use: ``#waveform: gaussian 1 1.2e9 my_gauss_pulse``.