The power rating of a resistor is determined by its physical size. The greater its surface area, the better it can dissipate energy, so the higher its power rating. Knowing its power rating and its resistance will determine the maximum voltage that can be applied to it in order to ensure the resulting current doesn't cause the resistor to overheat. This can be determined by manipulating the equation, P = U2/R.
Manipulate the following equation, to make I the subject: P = I2R, where P = power, I =current, and R = resistance.
LED's are light emmitting diodes. diodes have a voltage threshold that must be reached for them to fully "turn on". A resistor can be used to limit that voltage. As the voltage drop across the diode is increased above the turn on voltage (typically .5 - .7 volts), the diode will emmit light. The LED will only light up so far, so by turning the voltage up significantly more will have a very limitted payback in light output.
I think you mean 1/4W and 1/8W ratings for resistors. If so, it indicates wattage (power dissipation) ratings for resistors. Basically this specification for resistors shows maximum power that can be allowed to dissipate in the resistor. Wattage does not as such affect the value of resistor (it should remain with in % tolerance value specified when operated within specified wattage). ( P=I^2 x R). or (P = I x V) P=Power, I = Current, R= Resistance, V = Voltage Once you know the power rating, you can calcutate how much current can be passed through a resistor of specific value without causing a damage to the component or circuit. For long term reliability always it is advisable to design with a margin (for 1/4W or 250mW e.g. design so that it is always certain % less than the rated e.g. operate at 200mW or less) - Neeraj Sharma
To find the minimum power rating of a resistor, you can use the formula ( P = I^2 \times R ). Given that the current ( I ) is 400 mA (or 0.4 A) and the resistance ( R ) is 100 ohms, the power is calculated as ( P = (0.4)^2 \times 100 = 16 ) watts. Therefore, the minimum power rating for the resistor should be at least 16 watts to handle the maximum current safely. It's advisable to choose a resistor with a higher rating for added safety and reliability.
The voltage across the resistor is whatever voltage is applied. The only maximum here would be a voltage that would damage the resistor. If you think this might happen, you'll have to look up such a voltage from the data sheets.
Wattage.
There is no direct relationship.Power ('wattage') is a measure of the rate at which the resistor can dissipate energy; excessive power means that a resistor cannot dissipate energy fast enough to prevent its temperature becoming excessive -excessive enough to damage the resistor.As the rate at which a resistor can dissipate energy is determined by its physical size, a resistor's power rating(maximum continuous power it can handle without exceeding its rated temperature) depends on the physical size of the resistor.On the other hand, the resistance of a resistor is notaffected by its physical dimensions, as a resistor can be manufactured to any particular value of resistance for whatever physical size is necessary to achieve its rated power.If you know a resistor's rated power and its resistance, then you can calculate the maximum continuous current that resistor can handle without overheating (using the equation: power = current squared x resistance).
Manipulate the following equation, to make I the subject: P = I2R, where P = power, I =current, and R = resistance.
This depends on the tolerance rating of the resistor. There's 1, 2, 5, 10% tolerances. For tighter tolerances, you pay a premium - you can get tolerances as close as .1%. This is defined by one of the bands on the resistor. For a 10% tolerance, the maximum resistance of a 680 ohm resistor could be 748 ohms.
LED's are light emmitting diodes. diodes have a voltage threshold that must be reached for them to fully "turn on". A resistor can be used to limit that voltage. As the voltage drop across the diode is increased above the turn on voltage (typically .5 - .7 volts), the diode will emmit light. The LED will only light up so far, so by turning the voltage up significantly more will have a very limitted payback in light output.
Resistance wise, the rated wattages are immaterial. When calculating the amount of power the two of them would be able to dissipate, (or the maximum current) you would have to use V=IR and P=VI to work out which resistor would run into it's wattage rating first.
As current flowing through carbin composition resistor increses then resistance will decrese as the function of resistance is to oppose the flow of current.....AnswerA resistor is termed a 'linear' or 'ohmic' device, which means its resistance stays constant over a wide range of current variation -in other words, it obeys Ohm's Law up to the maximum current is designed to handle. If this were not the case, then the resistor would not be suitable for many applications. The maximum current it is designed to carry, before its resistance changes beyond its tolerance, is determined by its physical size, as the larger its surface area, the more efficiently it can dissipate heat.
The maximum wattage of an airplane power outlet is typically around 75-150 watts.
By attaching a resistance in parallel connection with the galvanometer. Or when a low resistor connected in parallel with galvanometer ,the galvanometer is converted in ammeter. and the resistor is called shunt resistance.
The maximum wattage on one socket generally ranges from 1500 to 1800 watts. It is important to check the specific rating of the socket to ensure that it can safely handle the wattage of the device you are connecting. Exceeding the maximum wattage can lead to overheating and potential fire hazards.
To determine the value of Stabilizing resistor Rs = Vs/Is = If(Rct +2Rl)/Is Where, Rs = resistance value of the stabilizing resistor Vs = voltage at which the relay will operate Is = current flowing through the stabilizing resitor and the relay If = maximum secondary fault current magnitude Rct = internal resistance of the current transformer Rl = resistance of attached wire leads
The maximum wattage cap for the ceiling fan light is typically around 60 watts.