## Why does a filament lamp graph curve?

A Filament Lamp Here the graph curves because as the filament heats it’s resistance goes up (the resistance of the filament is changing).

### What is the power factor of filament lamp?

unity
Others are designed for operation at the grid voltage (see Figure 3). Incandescent lamps are purely resistive loads, i.e., they have a power factor of unity, and there are no reactive currents.

#### Why do filament lamps have high resistance?

As the filament heats up, it is more difficult for the electrons to get through the filament because it’s atoms are moving so much, and because resistance measures how easily a current passes, the resistance goes up.

Does filament lamp obey Ohm’s law?

The filament lamp does not follow Ohm’s Law. Its resistance increases as the temperature of its filament increases. So the current flowing through a filament lamp is not directly proportional to the voltage across it.

What is the power factor of LED lamp?

LED lighting systems are driven (ballasted) by electronic LED drivers which have an inherently capacitive electrical characteristic. These drivers have an integrated active power factor corrector, resulting in a high-power factor of around 0.99 (same applies for electronic ballasts for HID lamps).

## Why does the resistance of a filament lamp change as the current increases?

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.

### Does tungsten have high resistance?

Pure tungsten is used in bulbs. Light is radiated from the bulb-filaments as a drop in electrical energy of the circuit. It is a fact that we use tungsten for a filament. Tungsten has a high melting point and high resistivity.

#### How is the I-V graph of a filament lamp?

[ Note: I-V graph is current-voltage characteristic] Now, let’s discuss in detail. In the I-V graph of filament lamp for a small voltage, the current is proportional to it. That is plotted by the straight-line portion of the graph through the origin.

Why does the resistance of a filament lamp increase with temperature?

Resistance of the filament lamp increase with temperature. Reason: As the potential difference across a filament lamp increases, the current increases and the energy dissipated, as heat, increases, resulting in a higher temperature.

How to identify I-V graph of a thermistor?

In the I-V graph of filament lamp for a small voltage, the current is proportional to it. That is plotted by the straight-line portion of the graph through the origin. At higher voltages, a larger current is driven through the lamp filament wire and the wire gets heated up due to the high current flow.

## What is the I-V graph of a metallic conductor?

The I-V graph of metallic conductor is a straight line pass through the origin. They obey Ohm’s Law, having resistance that is independent of current.