Electric field (E) is in the positive z-direction, magnetic field (B) is in the positive Y-direction and the velocity of the proton is in the positive X-direction. What is the direction of the electric force? magnetic force?

Question

anonymous · Answer

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anonymous · Answer

Do you have any lead? 

$$\vec F_{elec} = q \vec E $$
what does this vector equation tell u about the direction of the force?

sidsiddhartha · Answer

first u need to know what is lorentz force 
do u have any idea?

anonymous · Answer

@mashy electric force is same with the direction of the electric field and i'm not sure about the direction of the magnetic field because of i don't know where the current is

anonymous · Answer

@sidsiddhartha i haven't learned lorentz force yet, what is it?

anonymous · Answer

current direction is the same as direction of motion of postive charges !

sidsiddhartha · Answer

if u consider a particle in a electric field then the force F can act on it and it doesnot depends on that the particle is moving(dynamic) or at rest (static) 
and the force acting on it is
$$F=QE$$
but cases are diffrent for particles in magnetic field
magnetic field force acts only on a moving particle and this force is perpendicular to both velocity V and field B
anf this force it known as lorentz force
$$F=Q(E+V   cross    B)$$

anonymous · Answer

oh so the magnetic force is in the z-direction also, thanks

anonymous · Answer

@sidsiddhartha so it's basically the sum of the two forces? O.o

sidsiddhartha · Answer

so graph will look like|dw:1400347597109:dw|
yes and the motion of the particle will be spiral