• Open Access

Upper-division student difficulties with the Dirac delta function

Bethany R. Wilcox and Steven J. Pollock
Phys. Rev. ST Phys. Educ. Res. 11, 010108 – Published 9 March 2015

Abstract

The Dirac delta function is a standard mathematical tool that appears repeatedly in the undergraduate physics curriculum in multiple topical areas including electrostatics, and quantum mechanics. While Dirac delta functions are often introduced in order to simplify a problem mathematically, students still struggle to manipulate and interpret them. To characterize student difficulties with the delta function at the upper-division level, we examined students’ responses to traditional exam questions and a standardized conceptual assessment, and conducted think-aloud interviews. Our analysis was guided by an analytical framework that focuses on how students activate, construct, execute, and reflect on the Dirac delta function in the context of problem solving in physics. Here, we focus on student difficulties using the delta function to express charge distributions in the context of junior-level electrostatics. Common challenges included invoking the delta function spontaneously, translating a description of a charge distribution into a mathematical expression using delta functions, integrating 3D or non-Cartesian delta function expressions, and recognizing that the delta function can have units. We also briefly discuss implications of these difficulties for instruction.

  • Figure
  • Received 12 January 2015

DOI:https://doi.org/10.1103/PhysRevSTPER.11.010108

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Authors & Affiliations

Bethany R. Wilcox and Steven J. Pollock

  • Department of Physics, University of Colorado, 390 UCB, Boulder, Colorado 80309, USA

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Issue

Vol. 11, Iss. 1 — January - June 2015

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