What is a noun clause?

[Sonia*]

Hi Teacher,

1. Fatigue is where the metal has become weak trough stress. (Incorrect)

2. Fatigue occurs when the metal has become weak through stress. (correct)

Please guide me, why the second sentence is correct.

3. What is a noun clause? Please give me some examples.

Thanks a million in advance!

Sonia*

[Mister Micawber]

1. Fatigue is where the metal has become weak through stress. -- Not 'incorrect', 'where' is just casual register, and should be avoided in careful writing, as with #2
2. Fatigue occurs when the metal has become weak through stress. -- More standard.

3. What is a noun clause? Please give me some examples.-- It is a clause used as a noun. There are examples HERE.
_________________
Native English teacher at Mister Micawber's

[Sonia*]

Thanks a lot, Mister Micawber!

Best Wishes!
Sonia*

[Torsten]

Hi Sonia,

Please use a meaningful title for your questions: What is a meaningful message title and why is it important?

TOEIC listening, photographs: Big cranes

[Sonia*]