Why do trains spark in the snow?

Related questions

1. Do trains go in reverse?
2. Can you run an engine backwards?
3. Can steam trains go backwards?
4. What will be the fare of bullet train in India?
5. Can you turn crankshaft backwards?
6. How much HP does a train have?
7. Why are trains so slow?
8. How much weight can a steam train pull?
9. Are train tracks heated?
10. Is Indian bullet train Maglev?

Tags

1. #radio
2. #pantograph
3. #overhead
4. #create
5. #contact
6. #interference
7. #train
8. #moment
9. #between
10. #shaking
11. #because
12. #builds
13. #occur
14. #sparks
15. #winter