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answer question number 2 and show answer step by step ENS 356 MEdherm Exam (Fall

ID: 1789138 • Letter: A

Question

answer question number 2 and show answer step by step

ENS 356 MEdherm Exam (Fall, 2017) Your name Pat I Simply Questions (10pts each) CSI, CUNY Professor i . How to turn a scalar field into a vector field? List all the possibilis you hink of For two vectors A and B of finite amplitudes, can A-,,-0 and A“-o hold simultaneously? Give your reasoning 2 3. How are sound and light related to electromagnetic fields? Write down the x-component of the Faraday's law and the y-component of the Ampere's (circuital) law. Part II Calculations (20 pts each) 1. A beam of charged particles pass through perpendicular electrical field , E (E > 0) and magnetic field B = B (B > 0) One observes that the electrons go in straight lines. What can we say about (1) the direction, (2) the speed, and (3) the charge of the particles? (Hint: What is the force on the particles when they go in straight lines?)

Explanation / Answer


Vectors A,B

we know the vector product of two vectors A,B is A X B = A*B sin theta

where theta is the angle between the vectors  

and

the scalar product is A.B = A*B cos theta


when the angle between the vectors is zero then the vector product is zero an same time the sacalar product is maximum = A*B

if the angle between the vectors is 90 degrees then the scalar product is = A*B cos90 = zero and the vector product is maximum = A*Bsin90 = A*B