In both magnitude and direction since acceleration is a vector quantity
The arrows in models of magnetic and electric fields show both their magnitude and direction.
In Physics, a vector refers to a quantity that has both magnitude and direction. Hence, a vector always points in a given direction. The direction in which the arrow points is the direction of the vector in space.
In models of magnetic and electric fields, field vectors depicted by arrows because they represent both their magnitude and direction. The length of the arrow shows magnitude.
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The answer is b. The crest.
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