Question

The light waves have that particular interference from question #1 because they are emitted _____.

Answer 1

I am attaching the rest of your question so it makes sense, 

Since lasers are made from stacking light waves that add together into a larger wave due to CONSTRUCTIVE INTERFERENCE.

Then, light waves have that constructive interference (from question #1) because they are emitted IN PHASE with each other.

This means that they arrive at the same point of space with the same characteristics and their effects do not cancel each other, but the opposite, their intensity increases.

Answer 2

Answer;

- In phase

Explanation;

Constructive interference occurs when the maxima of two waves add together (the two waves are in phase), so that the amplitude of the resulting wave is equal to the sum of the individual amplitudes.

Constructive interference occurs when waves come together so that they are in phase with each other. This means that their oscillations at a given point are in the same direction, the resulting amplitude at that point being much larger than the amplitude of an individual wave.

Therefore; For two waves of equal amplitude interfering constructively, the resulting amplitude is twice as large as the amplitude of an individual wave.