In: Physics
Consider the Electric field due to a line distribution of charge to be dE
Charge (total)=Q
Charge per unit length =Q/(0-(-l))=Q/l=
E at distance x on x-axis=9×109×Q/l×dy/r2
Where r=
dE=9×109Q/l×dy/(x2+y2)
Integrating both sides,
E=9×109Q/l
dy
E=9×109×Q/l×
dy
E=9×109×Q/l×tan-1(l/x)/x
2.Consider force on charge located at (2,0) because of 100 microcoulomb charge which is given by coulombs law as
F1=9×109×q1q2/r2=9×109×25×10-10/(22×10-4)=5.625kN
Similarly Force on charge 25 micro coulomb by charge -170 microC(F2)=-170×10-6×25×-6×9×109/((52+22)×10-4)=-13.189kN
Thus net force can obtained by principle of superposition of F1 and F2 as:
F=F1+F2=(-13.189+5.625)kN=7.564kN
2.Electric field at point (2,5) due to superposition of fields
=9×10^9×10-6((-1700000/4)+(1000000/29)+(250000/25))
=3825
+310.34
)+90
In terms
of vector notation
=4135.34i +400.34j kN
Value or magnitude=sqrt(41352+4002)
=4154.64kN
Therefore approx unit electric field vecto=4135.34/4154.6i+400.34÷4154.6j =0.995i+0.096jAns.
3.consider the proton and electron collide at xcm
We know that according to the relation
ma=-k.q1q2/r2
(equivalence of mechanical and electrostatic forces =》mvdv/dx=kq1q2/r2
=>1/2mv2=k.q1q2/r the negative sign in first equation is due to opposite sign of proton and electron.)
We can say distance of collision r is inversely proportional to mass m.
Thus the particles collides (since masses of proton>>>mass of electron.
near to proton and away from electron.
Thus point of collision is (0,3)=》x belongs ti 0<x<3 cm.