First of all, this was a bit garbled up, so it is sort of incomplete.
You gave me a total of 43 words, and I only counted 41 slots on the crossword graph itself, which is problematic.
I got as far as I could, but some of the words either weren't provided, or the spaces were made incorrectly for the length of these words.
Across:
2. (black / pitch)
7. conservation
9. radiation
12. crest
13 ?
14. whatever you wrote
15. dense
18. ? (radiant)
19. ? (radiant)
20. amperes
23. medium
25. density
26. ?
30. resistance
31. (pitch / black)
34. voltage
35. insulator
38. amplitudes
39. thermal
40. ?
41. wavelength
Down:
1. electromagnetic
3. (conduction/ convection)
4. (convection/ conduction)
5. (current/ radiation)
6. heat
7. chemical
8. transverse
10. energy
11. nuclear
12. circuit
16. electrical
17. electrons
21. mechanical
24. source
28. ?
32. rise
33. MRS CHEN
34. volts
36. sound
