The flash unit in a camera uses a special circuit to "step up$"$ the $3\mathrm{.}0$ V from the batteries to $370$ V $,$ which charges a capacitor. The capacitor is then discharged through a flashlamp. The discharge takes $12s,$ and the average power dissipated in the flashlamp is $1\mathrm{.}0{10}^{5}W$