Hi,
IC in the 2N5551 is about 16mA.
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Power doesn't flow in a transistor. It is dissipated. It heats up the transistor.
Only in device like a motor, a speaker or a LEDs it is (partly) transformed into other physical power (mechanical, noise, light)
For all other devices (that don't transform power), the dissipated = heating power is the current multiplied with the voltage across the device: P = I x U. This is true for DC....With AC it is more complicated..
Klaus