What happens to resistance of a lamp as the current increases?
A filament lamp is a common type of light bulb. … This heats up when an electric current passes through it, and produces light as a result. The resistance of a lamp increases as the temperature of its filament increases. The current flowing through a filament lamp is not directly proportional to the voltage across it.
Why does resistance of a bulb change?
The resistance of a light bulb changes with the temperature of the filament in the bulb, and therefore changes with the voltage applied to the bulb. The resistance when it is operating at its maximum voltage may be 10 times as much as when the bulb is “off”.
What is the resistance of the lamp?
The typical cold resistance of a 100 W incandescent lamp is about 9.5 ohms. If that resistance stayed the same with 120 V applied, Ohm’s Law tells us that the bulb would draw about 12.5 amps and dissipate about 1,500 watts.
Why does the resistance of the lamp increase as the potential difference across the lamp increases?
As the potential difference across the filament lamp increases the current across the lamp also increases due to Ohm’s law. The increase in current flow also causes the lamp to heat up which causes the resistance of the lamp to also increase.
Does resistance increase with current?
Current is inversely proportional to the resistance. A threefold increase in the resistance would cause a threefold decrease in the current.
Does current increase with resistance in a filament lamp?
Such a resistor is called an ohmic conductor. The current through a filament lamp is not directly proportional to the potential difference. This is because the filament gets hot, which causes the resistance to increase. … As the potential difference increases, the current no longer increases as much.
What happens to the current strength in a circuit when the resistance changes?
The relationship between resistance and the area of the cross section of a wire is inversely proportional . When resistance is increased in a circuit , for example by adding more electrical components , the current decreases as a result.
Why does resistance increase when potential difference increases?
The more energy that is put into the bulb, the harder it is for the current to flow – the resistance of the bulb increases. As the potential difference increases, so does the temperature of the thin wire inside the bulb, the filament.
How do you find the resistance of a lamp?
- To find the resistance of a component, you need to measure:
- The resistance is the ratio of potential difference to current. …
- For example, 3 A flows through a 240 V lamp. …
- resistance = 240 ÷ 3 = 80 Ω
- If you plot a graph of current against potential difference for a wire, you get a straight line.
What happens to the current as the voltage gets larger?
The current is directly proportional to the voltage and inversely proportional to the resistance. This means that increasing the voltage will cause the current to increase, while increasing the resistance will cause the current to decrease.
Do you expect the resistance of a light bulb to remain constant?
The filament in an incandescent bulb does not have a constant resistance. If you take a bulb and increase the voltage across it, the current increases too. An increase in current means the bulb gets hot—hot enough to glow.