O-Level Physics: Resistance Questions Answered

[Xcommunicated]

Well, these question are concerned with O-Level Physics.

- A bulb lights brighter when resistance is higher or lower?

- What about bulbs with filaments and thermistors?

- Is current directly proportional to resistance for filament lamps?

- When does current is directly proportional to resistance?

- When does current is inversely proportional to resistance?

- What is the relation between voltage and resistance (inversely, directly proportional)

Thanks.

 

[LowlyPion]

Welcome to PF.

So what are your thoughts on how to solve them?

 

[nlightner]

It's great to see an interest in O-Level Physics and resistance questions. Here are my responses to your questions:

1. A bulb will light brighter when resistance is lower. This is because a higher resistance will restrict the flow of current and reduce the amount of energy reaching the bulb, resulting in a dimmer light.

2. Bulbs with filaments and thermistors will also follow the same principle. The filament in a bulb has a higher resistance when cold, but as it heats up, the resistance decreases and allows more current to flow, resulting in a brighter light. Thermistors work in a similar way, with their resistance changing based on temperature.

3. For filament lamps, current is not directly proportional to resistance. This is because as the temperature of the filament increases, its resistance decreases and allows more current to flow. Therefore, the current and resistance are not directly proportional.

4. Current is directly proportional to resistance when the temperature of the material remains constant. This is known as Ohm's Law, which states that the current flowing through a conductor is directly proportional to the voltage and inversely proportional to the resistance.

5. Current is inversely proportional to resistance when the temperature of the material changes. This is because the resistance of the material changes with temperature, as seen in the examples of filament lamps and thermistors.

6. The relationship between voltage and resistance is inversely proportional. This means that as the resistance increases, the voltage will decrease, and vice versa. This can be seen in Ohm's Law, where the voltage is equal to the current multiplied by the resistance (V=IR).

I hope this helps clarify your questions about resistance in O-Level Physics. Keep exploring and asking questions!