Does a light bulb have constant resistance?
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. As the temperature increases, however, the resistance also increases.
What are the two examples of variable resistor?
Some examples of variable resistors are the volume control knob on a radio and a dimmer switch used for a light. Rheostats and potentiometers are two common types of these devices.
Is a light bulb a linear resistor?
a) The light bulb is non-linear because its resistance varies with increasing/sustained current.
Is a light bulb a conductor?
A light bulb is a device which produces light when electricity is passed through it. A bulb is made out of conductors as well as insulators. The filament, a thin tungsten wire in the light bulb, conducts electricity. Two wires that connect the supply to the mains are also conductors.
Why does a light bulb not obey Ohm’s law?
Resistance of non-ohmic components
In some small components, increasing the current raises the temperature, and we can’t be sure whether Ohm’s law is obeyed or not. An example of this is the filament light bulb, in which the temperature rises as the current is increased. Here, Ohm’s law cannot be applied.
Do light bulbs have high or low resistance?
Incandescent light bulbs have a small filament which when heated begins to glow and emit light. The reason the filament heats up is because it has a high resistance, which means that as electrons move through the filament, they lose a lot of energy.
Why does resistance change in a light bulb?
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 makes a resistor variable?
A variable resistor is a resistor of which the electric resistance value can be adjusted. … When only two terminals are used, it functions as a variable resistance and is called a rheostat. Electronically controlled variable resistors exist, which can be controlled electronically instead of by mechanical action.