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| Changing resistor |
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| nForce:
So I can change a 0.25 W resistor with a 2 W with the same resistance, but I can't change 2 W resistor with 0.25 W? Is this is same as capacitance and voltage at capacitors? |
| ArthurDent:
There needs to be more context but you can't almost randomly interchange components. Consider a 12 volt 1/4 watt incandescent lamp and a 120 volt 2 watt incandescent lamp. If you try to connect the 12 volt lamp to the 120 volt circuit, it will be very bright for a split second before it burns out. The voltage rating on a capacitor should not be exceeded and a capacitor shouldn't be used above perhaps 80% of its rating. Google can be of help here. http://www.learningaboutelectronics.com/Articles/What-does-the-voltage-rating-on-a-capacitor-mean . |
| Kirill V.:
The Maximum power dissipated of resistor means that this resistor able to dissipate a certain amount of heat into the environment per unit time (this is the power) for a long time. At the same time its main parameters do not degrade. Your question is not quite clear to me, could you formulate it in more detail? |
| Zero999:
--- Quote from: nForce on October 05, 2019, 01:14:05 pm ---So I can change a 0.25 W resistor with a 2 W with the same resistance, but I can't change 2 W resistor with 0.25 W? Is this is same as capacitance and voltage at capacitors? --- End quote --- Generally yes, in DC/low frequency applications a low power resistor can be exchanged for a much higher power one of the same resistance. However, at high frequencies, when the parasitics become significant, replacing small components with physically larger ones will create problems. |
| andy3055:
--- Quote from: nForce on October 05, 2019, 01:14:05 pm ---So I can change a 0.25 W resistor with a 2 W with the same resistance, but I can't change 2 W resistor with 0.25 W? Is this is same as capacitance and voltage at capacitors? --- End quote --- A simpler way to think of this would be to use the general formula W=VxI or I=W/V. Given that V remains constant, W is dependent on I. If W is lower, it means I has to go down as well. What that means is that the resistor with the lower W can pass only a lower current. Resistors are built so that they have different wattages for any given resistance as one need not use a physically large component taking up space. Now, to do that, the current carrying capacity has to be reduced. So, in other words, the 0.25 W will not be able to carry the same current as a 2 W resistor as it will over heat or burn down. I hope this helps. |
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