# PHYS -Electric Fields Physics Worksheet-Academy of Career Training .

9 Work Does this make sense? Negative Positive Direction Potential Energy Difference of movement EB-EA=kQq((1/rB) – (171A)) TA > B Negative (q moving (q charge is attracted towards towards Q) Q) Positive work is done by the field and goes into an increase in kinetic energy of a Negative Positive B>TA Positive (q moving (q charge is attracted so away from energy is required to move it Q) away from Q) Negative Negative rA> rB (q moving towards Q) Positive (q charge is repelled so energy is required to move it towards ) Positive work goes into moving a positive and a negative charge apart and increasing the potential energy Positive work goes into moving two negative charges together and increasing the potential energy Positive work is done by the field and goes into an increase in kinetic energy of q. Negative Negative B > TA Negative (q moving (a charge is repelled and away from moving away from Q) PRACTICE Q1a) Use Q = 1.5C, q = 1.0 x 10-C, TA = 2.0cm and r = 4.0cm. Calculate the electric force, the electric field strength for Q, the electric potential energy difference for some of the 8 scenarios above to help you understand the patterns. Q1b) These charged spheres have mass, but we can (and we do) ignore gravitational fields. Why? Here is a summary of all the possible scenarios. – 8 of them. Q is large relative to q so Q’s electric field affects q. Assume Q is stationary and q is free to move. A is initial separation and B is the final separation. Therefore, all the differences are final – initial. 1 1 Potential Energy Difference = Eg – En =kQ9 TE TA Q q Work Does this make sense? Positive Positive Direction Potential Energy Difference of EB – EA=kQq((1/rB) – (1/1A)) movement TA > B Positive (q moving (q charge is repelled so towards energy required to move it towards repulsive Q) Positive work Yes, you or goes into some external moving two force have to positive put in work to charges squeeze together and together two increasing positive the potential charges energy because they naturally repel each other Positive work Yes, these two is done by charges the field and naturally repel goes into an each other, so increase in a accelerates kinetic energy away from Q of q. due to the repulsive force/field. Positive Positive rB > TA Negative (q moving (charge is repelled and away from moving away from Q) Q) Positive Negative AB (q moving towards Q) Negative Positive work ( charge is attracted towards is done by Q) the field and goes into an increase in kinetic energy of a Positive Negative B > TA Positive (q moving (q charge is attracted so away from energy required to move it Q) away from ) Positive work goes into moving a positive and negative charges apart and increasing the potential energy ū=3,p, 2. For and v=(-9,12,p) V( determine the value of p when a) û and are collinear 3. Given 171=5 151=12 |+5|=13 and determine the value of 21-357 +5