Static vs Current
Describe the difference between static and current electricity
Static - build up and discharge of electrons
Current - continuous flow of electrons
What is the main difference between a wet cell and a dry cell
dry cell - paste electrolyte
wet cell - liquid electrolyte
Describe the difference between a series and parallel circuit
Series - electricity only flows in one path
Parallel - electricity flows through multiple paths
What type of energy is considered "waste" or "lost" energy from a lightbulb
Thermal (heat)
If a microwaves input energy is 30 J and useful output is 12 J, what is the percent of efficiency?
12/30 x 100 = 40 percent
Describe the 2 laws of electrical charges
1. Opposite charges attract
2. Like charges repel
What is an an electrode and electrolyte? What makes the best and electrodes electrolytes?
Allows for ion (charged particle) transport between the two electrodes that are reacting
Electrode - 2 different metals
Electrolyte - acidic or salt electrolyte
What is the purpose of a variable resistor?
Like a dimmer switch (gradually change the flow of electrons)
The blades of a fan turning is an example of what type of energy?
Mechanical
If a phone battery has 15 V and generates 3 A of current, how much power is generated all together? (include the unit!)
45 W
Describe and draw a picture of what happens in charge separation
Occurs when a charged object is near a neutral object, causing movement of electrons.
. ex. balloon on wall
Describe the difference between a conductor and an insulator
Conductors - allows the flow of electrons
Insulator - prevents the flow of electrons
Describe how the length and thickness of a wire impacts resistance...
ex. shorter wire means more/less resistance
ex. thicker wire means more/less resistance
Length: Longer wires have more resistance.
Diameter: Thicker wires have less resistance.
List the series of energy transformations of a battery powered electric heater
Chemical to Electrical to Thermal
Ms.Laser decided to bake the entire class a cake for being so well behaved. His oven is connected to a 400 V outlet. If the current flowing through the oven is 20 A, what is the resistance of the heating element?
20 ohms
Friction is an example of ............ and an example is ..........
Static electricity/ electrical discharge
- clothes in a drier
- socks on a carpet
Explain what happens to the resistance, current and voltage in both series and parallel circuits as more loads are added.
Series: Resistance increases, current decreases, voltage decreases per load (same overall)
Parallel: Resistance decreases, current increases, voltage stays the same
If you had two 6 volt batteries connected in serries with a light and ammeter reading 4 A, what is the resistance?
R = 12 V/4 A = 3 ohms
If 2 lights are arranged in both a parallel and series circuit, which one will have greater current and brighter lights? Do a drawing as well.
Parallel (less resistance)
A microwave oven has a power rating of 150 W. If you heat a cup of coffee for 50 sec at high, how many joules of electrical energy are converted into heat by the microwave?
E = P x t (seconds)
E = 150 W x 50 sec
E = 7500 J