Chapter 21 potential 第八章静电场 结论:静电场力做功与路径无关. The work done by electrostatic force is path independent The electrostatic force is a conservative force. 静电场是保守场
Chapter 21 potential 第八章静电场 The work done by electrostatic force is path independent. The electrostatic force is a conservative force. 结论：静电场力做功与路径无关. 静电场是保守场
Chapter 21 potential 第八章静电场 2) Circulation theorem:静电场的环路定理 在静电场中,电场强度沿闭合路径的线积分等于零。或 电场力移动单位电荷沿闭合路径一周所做的功为0。 The line integral of the electrostatic field around a closed loop is zero qE·d=qo「E·dl B AlB A2 B q(∫Ed+∫E·d)=0 2 alB B2A Edl=o
Chapter 21 potential 第八章静电场 2) Circulation theorem: 静电场的环路定理 0。 The line integral of the electrostatic field around a closed loop is zero. E A B A B q E l q E l 2 0 1 0 d d ( d d ) 0 1 2 0 A B B A q E l E l d 0 l E l 1 2 A B
Chapter 21 potential 第八章静电场 2. Electric Potential Energy电势能(PS15): Because electrostatic force is a conservative force an electric potential energy U can be introduced: 静电场是保守场,静电场力是保守力静电场力 所做的功就等于电荷电势能增量的负值. A→B AB.edI 如B (UR-U △U
Chapter 21 potential 第八章静电场 Because electrostatic force is a conservative force, an electric potential energy U can be introduced: 2. Electric Potential Energy 电势能(P515): 静电场是保守场，静电场力是保守力.静电场力 所做的功就等于电荷电势能增量的负值. U U U W q E l B A AB A B ( ) d 0 E 0 q A B
Chapter 21 potential 第八章静电场 To ensure U at a point, a reference potential energy should be chosen B=0,U 0 The U of charge g at arbitrary B point a= the work done by the fe during the move or/4g E charge g from a to infinity 试验电荷Q。在电场中某点的电势能,在数值上 就等于把它从该点移到零势能处静电场力所作的功 电势能的大小是相对的,电势能的差是绝对的
Chapter 21 potential 第八章静电场 To ensure U at a point, a reference potential energy should be chosen: 0, UB The U of charge q at arbitrary point a = the work done by the during the move of charge q from a to infinity. Fe AB A U q E l 0 d 试验电荷 在电场中某点的电势能，在数值上 就等于把它从该点移到零势能处静电场力所作的功. q0 电势能的大小是相对的，电势能的差是绝对的. E 0 q A B
Chapter 21 potential 第八章静电场 3. Electric Potential(P503): The physical quantity to represent property of field at any point - electric potential. A Electric potential at point a is the potential energy per unit charge. =0点 A E·dl A
Chapter 21 potential 第八章静电场 The physical quantity to represent property of field at any point —— electric potential. 3. Electric Potential (P503): q U V A A Electric potential at point a is the potential energy per unit charge. V E l V A A d 0 点 AB A U q E l 0 d