Question

(out of page) Figure 1 The long, straight wire shown in Figure 1 above is in the plane of the page and carries a current I. Point P is also in the plane of the page and is a perpendicular distance d from the wire. Gravitational effects are negligible. 1. With reference to the coordinate system in Figure 1, what is the direction of the magnetic field at point P due to the current in the wire? Justify your answer. A particle of mass m and positive charge a is initially moving parallel to the wire with a speed vo when it is at point P, as shown in Figure 2 below. m. (out of Dave

Answer 1

Given data: The given diagrom is Р y I 1. The direction of magnetic field at p is -Z direction, cos into the plane of papes perpendiculas to it, This is because of the right hand rule. The right hand rule says that if you put the thumb of your right hand in the direction of current, the curd of the rest of four figers will give you figers will give you the direction of Bi Now, the situation for the nex feroblem is; V ny d I To is in 'Negative x direction so- v=-v and magnetic field at p due to the

wire is in -z direction (from problems) BE-B, 2 Charge on the fasticle is q ( tve). Hence, the force on the pasticle is E = f(***) î, î k are renit vectors in X Y&z E?[Ev. î xE8 ks] directions. = quoB (îxê) & ix Å= In 2-quoB the direction of force on the particle of mass m is in -ve y directions answer NL (2) So, Vem And its magnitude is (3) Fim = q VOB ansker Since the magnetic force is acting én –y direction, balanced by 18 this magnetic force must be an electric force acting in ty direction, È q - (4 so, the direction of electric field is ty or Î. - answer

(5) Since a magnetic force of Fm = quo B is acting in -î direction and also the gravitatimal force of Fg = ng is in - so, the netelectic force to balance them is PE = Fm+ Fg quB + ng cand hence the electric field is ?E - quB + mg E- UB+ ng q anywer 44 gravitational effect is zero then E: 14