Constructive interference happens when this condition is satisfied:

This means that the difference in the distance traveled by the waves, from the slit to the screen, is equal to the whole multiple of the wavelength.
If we say that the distance between two interference fringes is much smaller than the distance from the slit to the screen, we can use the following approximation:

Finally for the bright spots we have:

The spacing between bright spots is:
Answer:
the Earth-Sun distance.
Explanation:
To measure parallax the base line distance that we need to know is the Earth-Sun distance. This distance is called 1 astronomical unit. This distance is 1.496×10^8 Km. So, this base line distance is necessary for the second link parallax.
The correct option is <u>D</u>.
Qualitative observations are observations that are made using our senses of sight, hearing, smell, taste and feel. These observations do not involve numbers or measurements of any kind.
The student's observations regarding the squirrel as is mentioned in options A, B and C involve measurements. Therefore these are not qualitative observations.
Option D, however, is made on the basis of sight, where the student observes the squirrel moving in a zigzag manner.
Therefore, of all the three observations, the student's observation that the squirrel ran in a zigzag pattern is the qualitative observation.
Answer:
B. change
Explanation:
In a chemical reaction, the bonds in the molecules break apart and form new ones, thus b is the correct answer because they change.
Answer:
agear lever or agear stick is the lever that you use to change gear in acar or other vehicle