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How much current is needed to light a bulb with 180 ohms of resistance using 120 volt power source?
Wiki User
∙ 13y ago
V = I x R so current I = 1/2 amp. I bet the bulb is rated at 60 W because Watts = Current x Voltage.
Where V = voltage (volt)
I = current (ampere)
R = resistance (ohm)
Your question isn't easy to answer. A lamp has two 'resistances': a 'cold' resistance, and a 'hot' resistance. Before it is energised, it is cold, so its resistance is low; when it is energised, it becomes very hot, and its resistance increases significantly. So, the question is whether your '240 ohms' is the cold resistance or the hot resistance. If it is the cold resistance, then a current of 0.5 A will flow through it for a fraction of a second, then its resistance will increase significantly, and the current will fall to a very much smaller value.
Wiki User
∙ 8y ago
Wiki User
∙ 13y agoBy Ohm's Law, current is voltage divided by resistance, so a bulb of 180 ohms across 120 volts would by 0.667 amperes.
That translates to 80 watts, which is a non-standard value, but that's what the numbers produce. However, you don't say if that resistance is cold resistance or hot resistance. It matters, because the cold temperature of a bulb is much lower than the hot temperature, so much so that a typical 60 watt bulb might actually pull 900 watts on initial start, with about 16 ohms cold and 240 ohms hot.
Wiki User
∙ 12y ago120 volts divided by 192 ohms is 0.625 amperes. 0.625 amperes times 120 volts is 75 watts. 75 watts is the same as 75 joules per second.
Wiki User
∙ 11y ago0.5A
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What voltage is required to sustain a current of 0.50 through a light bulb resistance of 190?
The voltage of a circuit with a resistance of 250 ohms and a current of 0.95 amps is 237.5 volts. Ohms's law: Voltage = Current times Resistance
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As more light bulbs are added in a series circuit, the effective resistance of the circuit increases. That causes the current leaving the source to decrease.
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With several lights in series across the power source, the full voltage of the power source is divided among the group of lights, in proportion to the resistance of each one, and the power available to each light depends on all of the others. The more lights in the series circuit, the less voltage each one gets, and the less power each can dissipate as light. ============================================ Another contributor added: Furthermore, power = voltage times current, and Current is equal to voltage divided by resistance. Putting lights in series increases the circuits resistance, which lowers the current, thus decreases power. This is why the overall light output of two lights in series will be less than a single light.
A light blub has a resistance of 96.8 ohms What current flows through the bulb when it is connected to a 120 V source of energy?
V = I x R so 120/96.8 = 1.24 Amps.
A string of 15 Christmas tree lights is connected in series to a 90 volt power source What is the value of the resistance of each light if the current flowing through the circuit is 2 amps?
33 ohms
Is a light bulb a soure of light?
Yes, a light bulb is a source of light. When current is going through the filament the resistance generates enough heat that the filament glows, producing light.
In what way the connections are made to get a higher output current from light?
A light doesn't output current, it "draws" current based on voltage and its resistance. Voltage = Current x Resistance or Current = Voltage / Resistance. (Ohm's Law)
What is needed to light a light bulb?
Electricity has to pass through the filament which, when it gets hot enough from resistance to the current, begins to glow and give off light.
What effect does decreased resistance have on a circuit?
resistance is the opposition to the flow of an electric current, therefore the current will decrease as the resistance increases. Resistance also creates heat. This is how the light globes in a circuit light up.
When the bulb is the resistance what this tells about the resistance?
An incandescent bulb has a filament that has a resistance. The value of the resistance determines the current that will flow for a given supply voltage. The heat generated by the current flowing through the filament gives off light. As the resistance of the filament decreases the current increases and you get more light.
Why is there zero current when a light bulb out?
there is no voltage and resistance
If the voltage is increased and current remains the same, what happens to the resistance?
According to ohms law (R=V/I) if voltage increases the resistance also increases .For example: If voltage (V) becomes 2 times the resistance (R) also increases becomes 2 times keeping the current (I) same
Why is there zero current when a light bulb burns out?
there is no voltage and resistance
In a series circuit when adding light bulbs does the current change?
Yes. The current is inversely proportional to the resistance. I = V / R where I is current, V is voltage, and R is resistance. Adding light bulbs adds resistance. Current is constant throughout a series circuit; it doesn't change no matter what. Voltage changes.
What would happen to the current in a simple circuit if a bulb with a higher resistance were used?
Ohm's law applies: Current = Voltage / Resistance As such if you double the resistance of the light bulb you end up with half as much current.
When light strikes a photocell does the resistance increase or decrease?
When light strikes a photocell, the resistance decreases, allowing current to flow more freely.
Which of the following condition exist in a circuit of pure resistance?
in a circuit of pure Resistance (r), IE. voltage source (12 v DC battery) and pure resistance (a light bulb). the voltage (v) and current (i) will be in phase. by adding capacitors and/or inductors to the circuit V and I will be pulled out of phase.
