Concept questions on Electric Fields and Dipole

PRS02 Electric field lines in the space surrounding a charge distribution show: 1. Directions of the forces that exist in space at all times. 2. Only directions in which static charges would accelerate when at points on those lines 3. Only directions in which moving charges would accelerate when at points on those lines. 4. Directions in which either static or moving charges would accelerate when passing through points on those lines. 5. Paths static or moving charges would take. PRS02 The force between the two charges is: 1) Attractive 2) Repulsive 3) Can’t tell without more information PRS02 E-Field of Two Equal Charges Electric field at point P is: 1. 2. 3. 4. 5. Don’t Know 3/2222ˆ4ekqsds=⎡⎤+⎢⎥⎣⎦Ej􀁇3/2222ˆ4ekqdds=−⎡⎤+⎢⎥⎣⎦Ei􀁇3/2222ˆ4ekqdds=⎡⎤+⎢⎥⎣⎦Ej􀁇3/2222ˆ4ekqsds=−⎡⎤+⎢⎥⎣⎦Ei􀁇PRS02 E-Field of Five Equal Charges Six equal positive charges q sit at the vertices of a regular hexagon with sides of length R. We remove the bottom charge. The electric field at the center of the hexagon (point P) is: 1. 2. 3. 4. 5. 6. Don’t know 22ˆkqR=E􀁇22ˆkqR=−E2ˆ=−E􀁇2ˆkq=E􀁇0=E􀁇􀁇PRS02 E-Field of a Dipole As you move to large distances r away from a dipole, the electric field will fall-off as: 1) 1/r2, just like a point charge 2) More rapidly than 1/r2 3) More slowly than 1/r2 4) Who knows? PRS02 An electric dipole, consisting of two equal and opposite point charges at the ends of an insulating rod, is free to rotate about a pivot point in the center. The rod is placed in a non-uniform electric field. The dipole will experience 1. a noticeable electric force and no noticeable electric torque 2. no noticeable electric force and a noticeable electric torque 3. a noticeable electric force and a noticeable electric torque 4. no noticeable electric force and no noticeable electric torque