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PRACTICE – Point Charges – BLANK
Problem 1 Look at the two point charges in the picture. a) Calculate the x - and y -components of the total electric field at the origin of the axes due to the two charges in the picture. b) Calculate the electric potential at the origin of the axes due to the two charges +7μC and
- 3 μC. c) Calculate the x - and y -components of the electric force on a charge of –5μC placed at the origin of the axes. d) Calculate the electric potential energy of the two charges +7μC and –3μC together with a charge of –5μC placed at the origin of the axes. e) Calculate the electric potential energy of a charge of –5μC placed at the origin of the axes. 4m 2m
- 3μC x y
Problem 2 Charge Q 1 and charge Q 2 are placed in the xy - plane as shown in the picture where you will find all the pertinent informations. a) Calculate the x - and y -components of the total electric field at point P due to charges Q 1 and Q 2. b) Calculate the x - and y -components of the electric force on a charge Q 3 =−9μC placed at point P. c) Calculate the electric potential at point P due to charges Q 1 and Q 2 alone. d) Calculate the electric potential energy of a charge Q 3 =−9μC placed at point P. Q 2 = −2μC 1.5 m Point P Q 1 = +3.5μC 3 m y x
Problem 4 Charge Q 1 and charge Q 2 are placed in the xy - plane as shown in the picture on the right hand side where you will find all the pertinent informations. a) Calculate the x - and y -components of the total electric field at point P due to charges Q 1 and Q 2. b) Calculate the x - and y -components of the electric force on a charge Q 3 =−15μC placed at point P. c) Calculate the electric potential at point P due to charges Q 1 and Q 2 alone. d) Calculate the electric potential energy of a charge Q 3 =−15μC placed at point P. e) Calculate the electric potential energy of the couple of charges Q 1 and Q 2 together with a charge Q 3 =−15μC placed at point P. Q 2 = −7μC 4 m Point P Q 1 = +5μC 8 m y x
Problem 5 Two point charges Q 1 and Q 2 are placed in the xy - plane as shown in the picture. Positions and values of the charges are given in the picture. a) Calculate the x - and y -components of the total electric field at the origin due to charges Q 1 and Q 2. b) Calculate the x - and y -components of the electric force on a charge Q 3 =−4μC placed at the origin. c) Calculate the electric potential at the origin due to charges Q 1 and Q 2 alone. d) Calculate the electric potential energy of a charge Q 3 =−4μC placed at the origin. e) What is the electric potential energy of the charges Q 1 and Q 2 alone when positioned as in the picture above? y = 7m Q 1 = +3μC Q 2 = −2μC x = -10m y x origin 35º
Problem 7 In the picture on the right hand side, charge Q 1 = -6nC is placed at point ( x = -4cm, y = 4cm), charge Q 2 = +3nC is placed at point ( x = -4cm, y = 0), and charge Q 3 = -3nC is placed at point ( x = 4cm, y = 0 ). a) Calculate the total electric field at point P due to the charges Q 1 , Q 2 , and Q 3. Give x- and y -components. b) Calculate the total electric potential at point P due to presence of the charges Q 1 , Q 2 , and Q 3. c) How much work would you need to do to bring together charges Q 1 , Q 2 , and Q 3 , and position them like in the picture above? Assume you start with all three charges infinitely far away from each other. d) If you only consider the charges Q 2 and Q 3 positioned like in the picture above, what is the electric potential at point P due to their presence? e) If you only consider the charges Q 2 and Q 3 positioned like in the picture above, what is the electric field at point P due to their presence? y Point P^ x
Q 2 = +3 nC (^) 4 cm 4 cm Q 3 = –3 nC Q 1 = –6 nC
4 cm
