1) Open Circuit d) A circuit with the switch turned to off or a circuit with any break A circuit (a circle) must be complete for the switch to be “on” if there is any break or open spot, it is an “open circuit”.
2) Closed Circuit f) A circuit with the switched turned on, or a completed circuit. A circuit (a circle) must be complete for the switch to be “on” if there are no breaks, it is a closed circle, or “closed circuit”
3) Battery a) A device using chemical energy to push current in a circuit. A battery acts as a pump to push electrons through a circuit. In the last unit, we learned that a battery is a source of potential (stored) electrical enerergy.
4) Resistance e) The ability to resist current flow. This is a property of materials that resists current flow, much like a kink in a hose or a bottle neck resists the flow of water. A resistor reduces the pressure (voltage) of the water flowing through it.
5) Resistor h) In a circuit diagram, an object that uses electrical energy is usually represented by one of these. Any object, a bulb, a toaster, a piece of electronics can be a resistor.
6) Ohm’s Law c) The mathematical relationship between current, voltage and resistance. Ohm’s law is represented by the equation: V = I x R, or I=V/R, or R = V/I
7) Conductor g) An object through which electricity passes easily Any passage of electricity is said to be conduction. If it is easy, then the object or material is a conductor.
8) Insulator b) An object that conducts electricity poorly Any passage of electricity is said to be conduction. If it does NOT conduct electricity easily, then it is an INSULATOR.
Question 9 A microwave uses a current of 4 amps to heat Mr. Franz’s coffee, The voltage in the wall outlet is 120 volts. Calculate the resistance of the microwave. Look at what we want, R R= V/I R=120 V / 4 A R=30 (ohms)
Question 10 A light bulb needs 2 amps to produce light. If the resistance of the bulb is 3 ohms, how many 1.5 volt batteries do you need to make it light? Look at what we want, V V=I x R V = 2A x 3 V = 6 V If each battery is 1.5 V, then we need 4 of them
Question 11/12 The diagram below pictures three identical light bulbs, each with a resistance of 1 ohm, which are connected by resistance-free wires. A 9-volt battery supplies energy to the circuit. The total resistance for the circuit shown in the figure is: Look at what we want, R For a series circuit, we just add the resistance R T = R 1 +R 2 +R 3 = 1 +1 +1 = 3
Question 13/14 The current for the circuit shown is: The voltage drop across each light bulb above is ____ volt(s).
Question 15 Suppose you connect more and more light bulbs in series to a battery. What happens to the brightness of each bulb as you add more bulbs?