(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Positive point charges q_1= 6.90 microC and q_2= 2.90 microC are moving relative to an observer at point P as shown in the figure. The distance from the observer to either charge is originally d = 0.190 m.The two charges are at the locations shown in the figure. Charge q_1 is moving at a speed of v_1 = 3.20×10^6 m/s and q_2 is moving at a speed of v_2 = 9.40×10^6 m/s.

a. What is the magnitude of the net magnetic field they produce at point P ?

b. What is the direction of the net magnetic field they produce at point P ?

2. Relevant equations

See below.

3. The attempt at a solution

I think I mixed up my signs for the cross product of v and r. Are the two fields in opposite directions? Any advice on those parts are appreciated.

B_1 = (mu_0/4*pi)*[(q*v vector*r vector)/(r^3)]

v vector = 3.20*10^6 m/s*i

r vector = (-0.190 m)*j

v vector*r vector = (3.20*10^6 m/s)i*(-0.190 m)j = -60800 m^2/s*k

B_1 = [(1*10^-7 T*m/A)*(6.90*10^-6 C)(-60800 m^2/s*k)]/[0.190 m]^3

= (-6.12*10^-5 T)*k ??

B_2 = (mu_0/4*pi)*[(q*v vector*r vector)/(r^3)]

v vector = -9.40*10^6 m/s*i

r = 0.190 m*j

v vector*r vector = (-9.40*10^6 m/s*i)*(0.190m*j) = -1786000 m^2/s

B_2 = [(1*10^-7 T*m/A)*(2.90*10^-6 C)(-1786000 m^2/s*k)]/[0.190 m]^3

= (-7.55*0^-5 T)*k ??

B_total = (-6.12*10^-5 T)*k - (-7.55*0^-5 T)*k = -(1.37*10^-4 T)*k out of the page?? (negative z-axis?)

Thanks.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Magnetic Field Intensity and Point Charges

**Physics Forums | Science Articles, Homework Help, Discussion**