Electronics > Beginners
Changing resistor
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.
Navigation
[0] Message Index
[#] Next page
Go to full version