Can you please help me with these? You must write an explanation as to why the a

Question

Can you please help me with these?

You must write an explanation as to why the answer that is the best answer, and the answer that is NOT the best answer

The best answer: The angle increases by a factor of 2. An explanation:

Not the best answer: The angle does not change. An explanation:

Q2: Light passes through a single slit. If the width of the slit is reduced, what happens to the width of the central bright fringe?

The best answer: The central bright fringe becomes wider, because the angle that locates the first dark fringe on either side of the central bright fringe becomes larger. An explanation:

Not the best answer: The width of the central bright fringe does not change, because it depends only on the wavelength of the light and not on the width of the slit. An explanation:

Q3: The drawing shows a positive and a negative point charge. The positive charge has the greater magnitude. Where on the line that passes through the chargers is one spot where the total electric filed is zero.

The best answer: To the left of the negative charge. An explanation:

Not the best answer: Between the chargers at the midpoint. An explanation:

Explanation / Answer

part a:

for double slit experiment,as wavelength is directly proportional to sin(theta) and using small angle approximation,

wavelength is directly proportional to angle theta.

as wavelength is doubled , angle also increases by factor of two.

hence this is the best answer.

as angle changes, the answer "angle does not change" is not the best answer.

part b:

width of the central bright fringe=wavelength*distance of the screen from the slit/slit width

as slit width is reduced, central bright fringe widens.

hence it is the best answer.

any other answer would be "not the best answer".

part c:
electric field due to negative charge is towards the charge

electric field due to positive charge is away from the charge.

so in between two charges, field is along the same direction and hence field can not be zero.

now, field will be zero either to the left of left charge or right of the right charge

electric field magnitude is directly proportional to charge magnitude and inversely proportional to square of the distance.

as negative charge is of lower magnitude, the point of zero electric field will be at a lower distance to negative charge as compared to positive charge

hence the best answer is to the left of the negative charge.

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