What happens to the resistance of a lamp when it is turned on and gets hot?
The resistance of a lamp is measured to be 30Ω when the lamp is cold. When the lamp is turned on and gets hot, its resistance increases. This increase in resistance occurs because as the temperature of the lamp rises, the atoms within the lamp vibrate more rapidly. This increased vibration causes the electrons to collide with the atoms more frequently, leading to a higher resistance in the lamp.
Reasons for Resistance Change:
Temperature Effect: One of the main reasons for the change in resistance of a lamp when it gets hot is the temperature effect. As the temperature of the lamp increases, the resistance also increases due to the greater atomic vibration.
Factors Affecting Resistance Change:
Type of Material: The resistance change in a lamp when it gets hot also depends on the material the lamp is made of. For example, the resistance of a tungsten filament bulb may increase by a factor of 10 when it is turned on, while the resistance of a fluorescent lamp may only increase by a factor of 2. This difference is due to the varying properties of the materials used in the lamps.
Understanding Resistance Increase:
Electron Collisions: The increase in resistance of a lamp when it gets hot can be attributed to the higher frequency of electron collisions with the vibrating atoms in the lamp. This increased collision rate impedes the flow of electrons, resulting in a higher resistance.
In conclusion, the resistance of a lamp changes when it is turned on and gets hot due to the temperature effect and the type of material used. Understanding these factors can help in predicting and explaining the variations in resistance that occur in different types of lamps.