Answer:
The phase difference is
Explanation:
From the question we are told that
The distance between the loudspeakers is 
The distance of the listener from the wall 
The frequency of the loudspeakers is 
The velocity of sound is 
The path difference of the sound wave that is getting to the listener is mathematically represented as

Substituting values


The phase difference is mathematically represented as
= 
Where
is the wavelength which is mathematically represented as

substituting value


Substituting value into the equation for phase difference
= 
Answer:
Image B represents the force on a positively charged particle caused by an approaching magnet.
Explanation:
The most fundamental law of magnetism is that like shafts repulse each other and dissimilar to posts pull in one another; this can without much of a stretch be seen by endeavoring to put like posts of two magnets together. Further attractive impacts additionally exist. On the off chance that a bar magnet is cut into two pieces, the pieces become singular magnets with inverse shafts. Also, pounding, warming or winding of the magnets can demagnetize them, on the grounds that such dealing with separates the direct game plan of the particles. A last law of magnetism alludes to maintenance; a long bar magnet will hold its magnetism longer than a short bar magnet. The domain theory of magnetism expresses that every single enormous magnet involve littler attractive districts, or domains. The attractive character of domains originates from the nearness of significantly littler units, called dipoles. Iotas are masterminded in such a manner in many materials that the attractive direction of one electron counteracts the direction of another; in any case, ferromagnetic substances, for example, iron are unique. The nuclear cosmetics of these substances is with the end goal that littler gatherings of particles unite as one into zones called domains; in these, all the electrons have the equivalent attractive direction.
Net force
As it's negative the box will move left
Look at the third one i think its the answer
When you rub inflated balloon with your hair or your kitten's fur, charge is induced on all over the balloon's surface. This is called "charging by friction" because you developed charges by rubbing to bodies with each other. It will also stick on your wall you can check it out. This is because of "unlike charges attract each other". Rubbed balloon and wall possessed unlike charges which made them stick together.