Heating from an electron beam injected into the transition region of an average quiet sun atmosphere. The rate of energy deposition per distance is plotted against the height above the photosphere, for different values of the lower cut-off energy E_c (panel a), initial pitch angle β₀ (panel b) and power-law index δ (panel c). In all cases, the beam originates 2.3 Mm above the photosphere with a power of P_beam = 10¹⁸ erg s⁻¹. Additionally we have used E_c = 2 keV for panels b and c, β₀ = 0° for panels a and c and δ = 4 for panels a and b. The dashed curve is the temperature profile. The atmosphere corresponds to model C of Fontenla et al. (1993), extrapolated to coronal temperatures.