Theoretical expressions are found for the displacement of points on an ideal clamped‐end string relative to the end points when the supports are given an acceleration normal to the string length att=0. The accelerations considered have the form of (1) the Heaviside unit function, (2) the Dirac &dgr; function, and (3) the doublet impulse function. Approximate formulas for the maximum displacement of the string are derived for each of the three cases. Possible applications of the results to the problem of filament‐grid shorts in certain vacuum tubes are briefly discussed.