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.
The resistance R in ohms (Ω) is equal to the voltage V in volts (V) divided by the current I in amps (A)
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).
Ohm's Law: Resistance in ohms is voltage in volts divided by current in amperes.
Ohm's Law: Resistance is voltage divided by current 110 volts divided by 0.4 amperes is 275 ohms.
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.)
To find the conductance using ohms law,you take the inverse of the resistance(/R)
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.
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)
Using Ohm's law V:IR .I:V/R..I:100/5-20...I-20ampere
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.
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).
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.
Current = voltage/resistance
Resistance of the circuit = (voltage across the circuit) divided by (current through the circuit)
Current can be calculated from its inter related parameters like voltage, resistance using ohms law V=IR.
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).