R
Rikard Bosnjakovic
- Jan 1, 1970
- 0
A thing struck me right now:
Consider a 10v-circuit with a 1A-load. This gives 10W dissipation (P = U*I
= 10 * 1 = 10).
Suppose I then want to strangle the current down to 0.5A. Ohm's law gives
me R = U/I = 10/0.5 = 20 ohm, so I add that one. With 0.5A load, the
dissipation is 10 * 0.5 = 5W.
For the sake of easy calculation, let's assume the circuit is perfectly
linear. Now for the question: Should the resistor be 5W, i.e. the latter
value above, or 10W, the first value?
I tried to figure it out but couldn't come up with a reasonable answer of
why I should pick the one or other size.
Consider a 10v-circuit with a 1A-load. This gives 10W dissipation (P = U*I
= 10 * 1 = 10).
Suppose I then want to strangle the current down to 0.5A. Ohm's law gives
me R = U/I = 10/0.5 = 20 ohm, so I add that one. With 0.5A load, the
dissipation is 10 * 0.5 = 5W.
For the sake of easy calculation, let's assume the circuit is perfectly
linear. Now for the question: Should the resistor be 5W, i.e. the latter
value above, or 10W, the first value?
I tried to figure it out but couldn't come up with a reasonable answer of
why I should pick the one or other size.