How do you calculate filament resistance?

Remember the resistance is measured at operating temperature. Use the equation P= V^2/R, where P is power, V is voltage, and R the resistance of the filament.

Why does the resistance of the filament increases with temperature?

The resistance of a filament lamp increases as the potential difference increases because the filament becomes hot. The movement of electrons (which is what causes the current) makes the atoms inside the filament vibrate faster and this makes the filament heat up.

What is the resistance of this filament?

As the filament within an incandescent lamp heats up, there is a significant change in the resistance between the off state and when it is operating. A typical 60W bulb operating at 250 volts will consume 0.24 amps and have a resistance of 1041Ω or thereabouts.

What is a cold filament?

The cold resistance of the filament is the resistance measured at Room temperature (typically 25 degrees Celsius) with a Multi-meter when the bulb is OFF and Cool. The HOT resistance is calculated by measuring voltage across and current through the filament when the bulb is ON and HOT. ( R=V/ I)

How does the resistance of the filament vary with the temperature?

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.

How does the resistance of the light bulbs differ when the bulbs are cold and when the bulbs are hot?

when bulbs are cold their resistance is very low. this causes a large current to go through the bulb when first turned on. The large current can burn out the filament. When the bulb is hot, the resistance goes up and the current decreases.

What is the cold and hot resistance of the filament?

The cold resistance of the filament is the resistance measured at Room temperature (typically 25 degrees Celsius) with a Multi-meter when the bulb is OFF and Cool. The HOT resistance is calculated by measuring voltage across and current through the filament when the bulb is ON and HOT.

Why is the resistance constant in a filament lamp?

The resistance is constant. 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. At high temperatures, the atoms in the filament vibrate more.

What happens to current as temperature increases in a filament?

At high temperatures, the atoms in the filament vibrate more. The electrons in the current now collide more with the atoms. More energy is needed to push the current through the filament. As the potential difference increases, the current no longer increases as much.

How does the current through a filament lamp depend on potential difference?

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. At high temperatures, the atoms in the filament vibrate more.