Table of Contents
- 1 Why does the resistance of a light bulb change as it heats up?
- 2 How does light bulb affect resistance?
- 3 Why does the resistance of the lamp increase as the potential difference across the lamp increases?
- 4 Why is higher resistance brighter?
- 5 What happens to the resistance of a lamp as the current increases?
- 6 What controls the brightness of a lamp?
Why does the resistance of a light bulb change as it heats up?
This is because the filament gets hot, which causes the resistance to increase. At high temperatures, the atoms in the filament vibrate more. The electrons in the current now collide more with the atoms. As the potential difference increases, the current no longer increases as much.
Why do light bulbs have high resistance?
It is the product of the current and the resistance that generates the heat (not only the resistance). So although a 100W lightbulb has a lower resistance, it will have a much larger current due to the low resistance. The product of the current and resistance will be high!
How does light bulb affect 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 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.
How does the resistance change with the brightness of a lamp?
The higher the resistance, the lower the current. Resistance is caused by the charge-carrying electrons colliding with the atoms in the conductor and bouncing off in different directions. The current in a bulb affects its brightness. The higher the current, the brighter the bulb.
Why is higher resistance brighter?
High resistance bulbs are brighter in series circuits Brightness depends on both current and voltage. So in series high resistance bulbs are brighter because they have a bigger p.d. across them. In parallel circuits low resistance bulbs are brighter because they have a bigger current through them for the same p.d.
Which light bulb has the higher resistance?
A 60-watt bulb has a higher electrical resistance than a 100-watt bulb. Because power is inversely proportional to resistance, when the power is less, the resistance is high.
What happens to the 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 increase when potential difference increases?
What controls the brightness of a lamp?
The brightness of the lamp (power) depends on two factors: The voltage and the current which flow through it. In Figure(A) as the variable reaistance increases its reaistance, the current which flow through the lamp will decrease and therefore its brightness decreases.