In contrast, changes in the input voltage or capacitance have no effect on discharge time, although they do have an effect on current density. As flash duration decreases, the electrical energy becomes concentrated into shorter pulses, so the current density will increase. Compensating for this usually requires lowering the capacitance as pulse duration decreases, and then raising the voltage proportionately in order to maintain a high enough energy-level. However, as pulse duration decreases, so does the "explosion energy" rating of the lamp, so the energy level must also be decreased to avoid destroying the lamp.