How does the temperature of the electrodes affect the spark in a sparking plug?

In summary, when connecting a car with a flat battery, you are advised to attach the positive connection to the positive connection on the working car and the negative connection to a piece of metal on the car in the engine bay.
  • #1
wentworth
1
0
When I connected my car with a flat battery to another working car I was told to attach the positive connection to the positive connection but I was told to attach the negative connection from the working car to a piece of metal on the car(preferably in the engine bay) instead of to the negative connection on the flat battery. I may have misunderstood but surely this breaks the circuit flow from battery to battery. If so then how does the flat battery become charged. Alternatively iof this does not break the circuit please explain why and also explin why it is that when you touch any metal on the car you don't get a shock because surely if there is a complete circuit it is flowing through metal in the car and should shock anyone who touches it
 
Physics news on Phys.org
  • #2
The battery negative terminal is connected to the car's metal frame, so electrically the frame is the same as the negative terminal.

The reason you are advised to connect the negative jumper to the frame is that it may spark while connecting. The frame is farther away from the battery so that a spark is less likely to ignite any hydrogen gas that the battery might be emitting.
 
  • Like
Likes Nugatory
  • #3
The battery negative terminal is connected to the car's metal frame...

...on the vast majority of cars that's true. On some old cars the positive is connected to the frame.
 
  • #4
  • #6
Thanks for that. It hadn't occurred to me that the temperature of the two electrodes in the plug might be different. Makes sense.
 
  • #7
CWatters said:
Thanks for that. It hadn't occurred to me that the temperature of the two electrodes in the plug might be different. Makes sense.

I think that quote of yours:

"An additional advantage of positive Earth was that a sparking plug sparks better with the Earth electrode positive."

was stated the wrong way round for making the point. It is surely the improved thermionic emission from the hotter, negative centre pin that would help with the spark.
 

Related to How does the temperature of the electrodes affect the spark in a sparking plug?

1. What are car jump leads used for?

Car jump leads, also known as jumper cables, are used to transfer electrical energy from one vehicle to another in order to start a car with a dead battery. They are an essential tool for emergency situations when a car battery has died and needs a boost to start the engine.

2. How do I use car jump leads?

To use car jump leads, follow these steps: 1. Park the car with the working battery close to the car with the dead battery, but do not let the cars touch. 2. Turn off the engines of both cars and remove the keys from the ignition. 3. Connect the red clamp of the jump lead to the positive terminal of the dead battery. 4. Connect the other end of the red clamp to the positive terminal of the working battery. 5. Connect the black clamp to the negative terminal of the working battery. 6. Connect the other end of the black clamp to an unpainted metal surface on the car with the dead battery. 7. Start the engine of the car with the working battery and let it run for a few minutes. 8. Attempt to start the car with the dead battery. 9. Once the car starts, carefully remove the jump leads in the reverse order that they were connected.

3. Can I use any type of jump leads for my car?

It is important to use the correct type of jump leads for your car. The gauge, or thickness, of the cables must be appropriate for your car's battery and electrical system. Using the wrong type of jump leads can cause damage to your car's electrical system or even result in a fire. It is recommended to use heavy-duty, 4 or 6 gauge jump leads for most cars.

4. How long do car jump leads last?

The lifespan of car jump leads depends on various factors such as the quality of the cables, frequency of use, and proper storage. On average, good quality jump leads can last for several years with proper use and maintenance. It is important to regularly inspect the cables for any signs of damage and replace them if necessary.

5. Are there any safety precautions I should take when using car jump leads?

Yes, there are a few safety precautions to keep in mind when using car jump leads. First, always make sure the engines of both cars are turned off and the keys are removed from the ignition. Also, never let the clamps touch each other or any metal surfaces while the jump leads are connected. This can cause a spark and potentially start a fire. Additionally, be careful when handling the jump leads as they can become hot during use. Finally, always follow the instructions provided by the manufacturer and use caution when handling electrical equipment.

Similar threads

B How is surface charge accumulated?
    • Electromagnetism
2
Replies
36
Views
3K
I How a Battery creates a Potential difference in an electrical current
    • Electromagnetism
Replies
14
Views
3K
Why would disconnecting the positive cable first on car battery cause sparks?
    • Electrical Engineering
2
Replies
54
Views
7K
I An attempt to understand the associated variable conventions in circuits
    • Electromagnetism
Replies
1
Views
873
What could be draining the car battery and how can it be fixed?
    • Electrical Engineering
Replies
8
Views
1K
Giving a jump start to a car - how does the circuit become complete?
    • Electrical Engineering
2
Replies
61
Views
7K
Why do the headlights on the car become dim when the car is starting?
    • Introductory Physics Homework Help
Replies
4
Views
352
Automotive Jumpstarting a dead car battery
    • Mechanical Engineering
Replies
7
Views
2K
Why isn't a capacitor an open circuit?
    • Electromagnetism
Replies
7
Views
3K
Earth grounded, where does the current flow?
    • Electrical Engineering
Replies
19
Views
3K

Hot Threads

Recent Insights

Back
Top