Choosing the right power value of resistors

[elefurtronik]

I would like to calculate the current flows over resistors to determine the wattage of the resistors. However, there is a capacitor at the end and I don't know how to calculate it exactly. I also attach the schematic.

[Kim Christensen]

Well, if that's 4.5V DC then the wattage is 0 if you ignore the very brief time that it takes to charge the capacitor.

[elefurtronik]

While charging the capacitor, the current will flow over resistors. How can I calculate this current during the charge? If I choose a low wattage for resistors, they can be burned in some cases. I would like to learn to calculate it for this reason.

[MarkS]

While charging the capacitor, the current will flow over resistors. How can I calculate this current during the charge? If I choose a low wattage for resistors, they can be burned in some cases. I would like to learn to calculate it for this reason.

What he's saying is that the current flowing through them, at 4.5v, is so negligible as to be of no concern. Current is voltage divided by resistance. Since the two resistors are in series, it's the same as having a single 6.9K resistor in the circuit. Using that, I = 4.5/6900 = 6.5217-4 or 0.00065217 amps. Wattage is voltage multiplied by current. At 0.00065217 amps, this comes out to 0.0029 watts. It might as well be zero. You'd be fine with 0.01 watt resistors. Just stick 1/4 watt resistors in the circuit and be done with it.

[WattsThat]

While charging the capacitor, the current will flow over resistors. How can I calculate this current during the charge? If I choose a low wattage for resistors, they can be burned in some cases. I would like to learn to calculate it for this reason.

The worst case, maximum current that can flow is given above in the reply by MarkS.

The current decreases very quickly, to zero in about .016 seconds.

Any series RC has a time constant that is R (in Ohms) x C (in Farads). The voltage at the capacitor will reach the applied voltage in about 5 time constants.

[MarkS]

Completely forgot to factor in time...