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10. A positive charge (small sphere) q22+10nC, m=lg is in a uniform electric fie

ID: 3280218 • Letter: 1

Question

10. A positive charge (small sphere) q22+10nC, m=lg is in a uniform electric field directed along x-axis. Another force, in addition to the electric force, acts on the sphere so that when its released, it moves in the direction opposite to the direction of electric field. After it moved 10 cm, the additional force has done 5x10J of work and the sphere has 2x103) of kinetic energy. What work was done by the electric field? What is the potential difference between the starting and ending points? What is the magnitude of the electric field?

Explanation / Answer

work done by all forces = change in KE

work done by electric field + work done by additional force = 2e-5

Work done by electric field = 2e-5 - 5e-5

= -3*10^-5 J

potential difference V = W/Q = 3e-5/10e-9 = 3000 V

magnitude of electric field = V/d = 3000/0.10 = 3*10^4 V/m