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By Ohm's law, resistance is voltage divided by current, so the resistance of a light bulb can be measured by observing the voltage across it simultaneously with observing the current through it.
Interestingly, the hot resistance is significantly different that the cold resistance, so measuring resistance with an ohmmeter will not give a meaningful resistance.
This is because the resistance of a light bulb has a positive temperature coefficient. Take a typical 60 W 120V light bulb, for instance... Its cold resistance is about 16 Ohms. Calculate current and power at 120 V and you get 7.5 A and 900 W. The truth is that at 60 W, the bulb pulls 0.5 A and has a resistance of 240 Ohms.
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What must know to calculate current using Ohms law?
The resistance R in ohms (Ω) is equal to the voltage V in volts (V) divided by the current I in amps (A)
How do you find resistance when you have current and resistance total?
If you are looking for the resistance of each resistor in either a series circuit or a parallel circuit you must measure the current I and the voltage V for each resistor. Then calculate its resistance using Ohms Law R = V / I where I = current (Amps), V = voltage (Volts) and R= resistance (Ohms).
What is the equation of resistance?
Ohm's Law: Resistance in ohms is voltage in volts divided by current in amperes.
What is the resistance of an electric lamp that takes in a current of 0.40 ampere when 110 volts is applied?
Ohm's Law: Resistance is voltage divided by current 110 volts divided by 0.4 amperes is 275 ohms.
What is the Unit of resistance measured in?
Resistance is measured in ohms.By Ohm's law, resistance is voltage divided by current, which is (joules per coulomb) divided by (coulombs per second), which is joules-seconds divided by coulombs squared. (It is easier to just say ohms.)
How do you find conductance using ohms law?
To find the conductance using ohms law,you take the inverse of the resistance(/R)
What is resistance measured in a unit called?
Ohms. It can also be calculated using Ohm's Law. V=I/R where V is voltage in Volts, I is current in Amps, and R is resistance in Ohms.
Did you know the Laws of resistance?
Ohms law.
What must know to calculate current using Ohms law?
The resistance R in ohms (Ω) is equal to the voltage V in volts (V) divided by the current I in amps (A)
What is the current in a 100 volt circuit with 25 ohms of resistance?
Using Ohm's law V:IR .I:V/R..I:100/5-20...I-20ampere
There is a current of 0.83 A through a light bulb in a 120 V circuit What is the resistance of this light bulb?
If a lightbulb has a resistance of 250 ohms, the voltage required for the bulb to draw a current of 0.5 A is 125 V. (Ohm's law: voltage equals current times resistance)Unfortunately, its more complicated than that...Is the resistance of 250 ohms the hot resistance or the cold resistance? It matters. It matters very much.Light bulbs have a dramatic positive resistance to temperature coefficient. It is not uncommon for the instantaneous on power to be 10 or 20 times the nominal value.So, if the 250 ohms is the measured resistance while operating at a current of 0.5 A, then 125 V is the correct answer. If the resistance is the cold resistance, you need to go back and find out the hot resistance at the desired operating point.
What is the resistance of a hair dryer that draws 12A when plugged into a 220V line?
The resistance can be calculated using Ohm's Law: resistance = voltage / current. In this case, the resistance of the hair dryer would be 18.33 ohms (220V / 12A).
How many volts are required to push 3 amps through a resistance of 4 ohms?
The voltage required can be calculated using Ohm's Law, V = I * R, where V is the voltage, I is the current (3 amps), and R is the resistance (4 ohms). So, V = 3 * 4 = 12 volts.
What is the Mathematical formula for OHMS law?
Current = voltage/resistance
Using ohm's law what is the formula to find the resistance in a circuit?
Resistance of the circuit = (voltage across the circuit) divided by (current through the circuit)
How do you calculate a current?
Current can be calculated from its inter related parameters like voltage, resistance using ohms law V=IR.
How do you find resistance when you have current and resistance total?
If you are looking for the resistance of each resistor in either a series circuit or a parallel circuit you must measure the current I and the voltage V for each resistor. Then calculate its resistance using Ohms Law R = V / I where I = current (Amps), V = voltage (Volts) and R= resistance (Ohms).
