Physical Science Chapter 20 Electricity

Physical Science – Chapter 20 – Electricity

Explain how lighting and “static cling” are similar. ______Electric Charge I. Electric charge = ______List the two types of electric charge and the subatomic particle associated with them: 1. ______2. ______Explain how a net electric charge is produced.______Look at Figure 2: What is the overall charge if the atom loses an electron?______The SI unit for electric charge: ______which equals ______Electric Forces I. Electric force = ______Like charges______, and opposite charges ______. Electric Field I. Electric field = ______Identify the two factors that the strength of an electric field depends on: 1. ______2. ______Static Electricity and Charging I. Static electricity = ______List the 3 ways charge can be transferred: 1. ______2. ______3. ______Explain the law of conservation of charge.______Charging by Friction Look at Figure 5A on page 602: Explain how the balloon and hair picked up a net charge. ______Charging by Contact Look at Figure 5B on page 602: Explain why the girl’s hairs repel each other. ______Charging by Induction Induction= ______Look at Figure 6 on page 603: What would happen if the hand had a net positive charge?______Write a paragraph explaining the series of events that may cause you to receive a shock from a metal doorknob on a winter day. Provide your explanation using at least 5-6 sentences, the correct grammar and punctuation.10 pts. ______

Assignment: Complete the following. 1. Explain how static discharge occurs. ______2. When a glass rod is rubbed with neutral silk, the glass becomes positively charged. What charge does the silk now have? Explain. ______3. How does the electric force between two charged objects change if you double the distance between the objects? Explain. ______4. Explain what determines the direction of the electric field near a charge. ______5. Explain how a charged object can cause charges to move within an uncharged object.______

Electric Current I. electric current = ______II. The SI unit of electric current is:______This equals:______III. List the two types of current: 1. ______2. ______Direct current= ______Alternating current= ______Conductors and Insulators Electrical conductor= ______Electrical insulator=______Give examples, not listed in your book, for good electrical conductors: 1.______,2.______, 3. ______Give examples, not listed in your book, for good electrical insulators: 1.______,2.______, 3. ______Resistance Resistance= ______I. SI unit for resistance is: ______II. List the factors that affect resistance and explain why they affect it. 1. ______2. ______3. ______Superconductor = ______Voltage Explain what the potential energy of a charge depends on and what direction the charge flows. ______Potential difference: ______How is potential difference measured? ______Voltage: ______In order for ______in a conducting wire, the wire must be ______in a ______that includes a source of ______. Voltage Sources List three common voltage sources: 1. ______, 2. ______, 3.______Battery=______A voltage drop is the same as a ______. Ohm’s Law Ohm’s law=______In the box below, write the equations for Ohm’s law:

SI units for: Current= ______Resistance=______Voltage = ______Explain how voltage is related to resistance and current. ______

Assignment: Complete the following. 1. What causes charge to flow? ______2. Suppose you have two wires of equal length made from the same material. How is it possible for the wire to have different resistances? Explain. ______3. Explain why a wire becomes warmer when charges flow through it. ______

Circuit Diagrams Electric circuit =______Explain what a circuit diagram shows. ______Describe how an open circuit is different from a closed circuit ______How is the direction of current defined? ______Look at figure 12 on page 610. Which symbol represents a light bulb? ______Series Circuits Series circuit=______Explain what happens when you add bulbs to a series circuit. Be sure to address resistance, current, and intensity of the bulbs.______Parallel Circuits Parallel circuit= ______Two bulbs connected in parallel shine more brightly than when they are connected to the same voltage source in series. Explain why this doesn’t violate the law of conservation of energy.______Power and Energy Calculations Recall that power is the rate of doing work. Electric power= ______SI unit for electric power: ______In the box below, write the equation for electric power:

Assignment: Complete the following. SHOW YOUR WORK! CIRCLE YOUR FINAL ANSWER 1. A clothes dryer uses about 27 amps of current from a 240-volt line How much power does it use?

2. A camcorder has a power rating of 2.3 watts. If the output voltage from its battery is 7.2 volts, what current does it use?

3. A power tool uses about 12 amps of current and has a power rating of 1440 watts. What voltage does the tool require?

4. A lamp has a voltage of 120 V across it and uses a current of 0.5 A. What is the power used by the lamp?

5. A 1.5 V battery provides 0.067 A of current for a calculator. What is the calculator’s power rating?

Do all appliances use the same amount of power? Explain ______

Describe how you can calculate the electrical energy used by an appliance.______

In the box below, write the equation for electrical energy:

What SI unit does the power company use to determine your monthly electric bill? ______. What does it equal? ______

Assignment: Complete the following. SHOW YOUR WORK! CIRCLE YOUR FINAL ANSWER 1. A stereo receiver uses a current of 2.2 amps from a 120–volt line. What is its power?

2. A television connected to a 120-volt line uses 102 watts of power. How much current flows through it?

Electrical Safety Describe the factors that help make electrical energy safe and give a brief description of them. 1. ______2. ______3. ______4. ______5. ______

What is the average voltage found in home circuits? ______Grounding=______

Assignment: Complete the following. 1. A person plugs a fan into a wall socket and turns it on. Suddenly, the lights go out in several rooms of the house. Explain what has probably happened and what can be done to fix it. ______2. The power rating on an electric oven is 9300 watts. If the oven is plugged into a 240-volt line, how much current does it use? What is the resistance of the oven? Show your work.