As You Come In… A negative charge is to be placed between a -3.0 C charge and a +8.0 C. Where can the charge be placed, if anywhere, such that it will not move from where it is set?
Challenge: Four-Body Charge Problem Four charges are placed at the corners of a square with sides of 5.0 mm. The top left and bottom right charges have a charge of +3.0 C. What would the charge at the bottom left corner of the square need to be such that the top right charge does not move away? q 1 = +3.0 C q 4 = +3.0 Cq 3 = ? q2q2 x y
Challenge: Four-Body Charge Problem Four charges are placed at the corners of a square with sides of 5.0 mm. The top left and bottom right charges have a charge of +3.0 C. What would the charge at the bottom left corner of the square need to be such that the top right charge does not move away? q 1 = +3.0 C q 4 = +3.0 Cq 3 = ? q2q2 x y Σ F E = 0 N F E1 F E4 + F E3
Challenge: Four-Body Charge Problem Four charges are placed at the corners of a square with sides of 5.0 mm. The top left and bottom right charges have a charge of +3.0 C. What would the charge at the bottom left corner of the square need to be such that the top right charge does not move away? q 1 = +3.0 C q 4 = +3.0 Cq 3 = ? q2q2 x y Σ F E = 0 N F E1 F E4 - F E3
Challenge: Four-Body Charge Problem Four charges are placed at the corners of a square with sides of 5.0 mm. The top left and bottom right charges have a charge of +3.0 C. What would the charge at the bottom left corner of the square need to be such that the top right charge does not move away? q 1 = +3.0 C q 4 = +3.0 Cq 3 = -?? C r 1 = m r 4 = m r 3 = m q2q2 x y
Challenge: Four-Body Charge Problem Four charges are placed at the corners of a square with sides of 5.0 mm. The top left and bottom right charges have a charge of +3.0 C. What would the charge at the bottom left corner of the square need to be such that the top right charge does not move away? Did you get -8.5 Coulombs? q 1 = +3.0 C q 4 = +3.0 Cq 3 = -8.5 C r 1 = m r 4 = m r 3 = m q2q2 x y
Issues With An “N-Charge” Body Problem Impractical to work with discrete amounts of charge Also impractical to have stationary charges Problem: charge math is hard Potential solution: “charge flow” Image courtesy of:
As You Come In… Think about what is needed in order for an electrical device to work. Write as many concepts or ideas as you know about the topic.
“Charge Flow” Animated gif courtesy of:
Current André-Marie Ampère Image courtesy of
Current and Electrons Recall the charge of an electron q e = × C This means one electron (1 e - ) has × C of charge How many electrons would there be in 1 C of charge? #e - = 6.24 × electrons 1 Ampere: 6.24 × electrons passing through a point per second
Introduction to Circuits Flowing electrons (current) are EXTREMELY useful to humans Take the form of a circuit Electrical circuit: closed path through which electrical current flows from a voltage source Useful Concepts: Current Voltage Sources And a whole lot more! Stay tuned!
Power Image obtained from: James Watt
Power Within A Circuit Power = Voltage times Current
Using Power A light bulb is put into a circuit that is connected to a standard U.S. electrical socket. If 1.25 A of current is running through the light bulb, what is the wattage of the light bulb? P = V I
Using Power What amount of current is running through a night-light with a 40 W incandescent light bulb? P = V I
Resistance Image obtained from: Georg Ohm
Resistance Image obtained from: Georg Ohm
Using Resistance A simple circuit consists of an electrical appliance that is connected to a standard U.S. wall socket and has 10.0 mA of current running through it. What would the resistance of the electrical appliance be?
Using Resistance A simple circuit consisting of a 1.5 V battery and a 5.0 Ω resistor. What is the amount of current that is running through the resistor?
Resistance & Power What is the resistance of the tungsten filament in a 60 W light bulb plugged into your wall at home? P = V I
Capacitance
Image obtained from: Michael Faraday
Using Capacitance A simple circuit containing a 9.0 V battery also contains a capacitor. What is its capacitance if 6.0 µC of charge can be stored within it?
Using Capacitance A simple circuit consisting of a 1.5 V battery and a 5.0 nF capacitor is setup. How many electrons are stored within the plates of the capacitor? q e = × C