Electricity Basics
What is the name of the subatomic particle responsible for electricity?
Electrons
What must there be for a circuit to allow the flow of electrons?
It is a single closed loop
What is the formula for Ohm's Law?
V = IR, where V is voltage, I is current, and R is resistance
What is the purpose of a fuse in an electrical circuit?
It prevents excessive current by breaking the circuit when overloaded.
What is Faraday's Law?
A changing magnetic field induces an electric current in a conductor.
What type of material allows electricity to flow easily and why?
A conductor, because electrons are able to move freely between atoms
Draw a circuit with 2 lights in series and a battery
See board
If a circuit has a voltage of 12V and a resistance of 4Ω, what is the current?
I = V/R → 12V/4Ω = 3A
What is one common cause of electrical fires?
Overloaded circuits, short circuits, or faulty wiring.
If a magnet moves faster in a copper coil, what will happen to the current?
It will increase
What is the difference between voltage and current?
Voltage is like water pressure, and current is like the flow rate. This means that voltage is how many electrons are moving, and current is how fast they are moving.
Draw a simple circuit with 2 lights in parallel, with a switch and a battery
See board
A circuit has a 9V battery and two resistors (3Ω and 6Ω) in series. What is the total resistance?
3Ω + 6Ω = 9Ω
Why are electrical outlets in bathrooms required to have GFCI protection?
To prevent electrocution by shutting off power.
A transformer has a primary coil with 500 windings and a secondary coil with 50 windings. Is this a step-up or step-down transformer?
Step-down transformer because the secondary coil has fewer windings
Name 2 different types of devices that are used to store electrons, AKA provide voltage
Batteries (Cels) and Capacitors
Why are houses wired in parallel as opposed to series? Even though it is cheaper to wire in series.
Because in a series circuit, every bulb decreases in brightness, and if one goes out the rest of the house would go out.
If a circuit uses 120V and has a current of 2A, what is the power consumed?
P = VI → 120V × 2A = 240W
How does increasing the number of turns in the secondary coil of a transformer affect voltage?
It increases voltage, making it a step-up transformer.
DAILY DOUBLE
An ideal 100W transformer has an input current of 20A and an output voltage of 12V. Determine the input voltage, and the output current. and how many turns does the transformer have if there are 200 turns on the primary coil? Remember: Input power and output power are the same, so both sides of the transformer will be 100 Watts
Np=200. Ns=480
Ip= 20A. Is= 8.33
Vp= 5v. Vs= 12V
Why are transformers Important in power distribution?
They can increase or decrease the voltage of a circuit to prevent power outages or fires.
Why does the brightness if light bulbs in a series circuit decrease, but in a parallel circuit, it does not?
Because in a series circuit, the total resistance increases with each bulb, and in a parallel circuit it does not.
The current flowing in an appliance connected to a 120 V source is 2 A. How many kilowatt-hours of
electrical energy does the appliance use in 4 h? (2 equations used & convert watts to kW)
.96kwh
In a power grid, why is electricity transmitted at high voltages?
To transmit power to a large area or across long distances
A transformer has in input voltage of 120 V and an input current of 5A. The output voltage is 11.9V and the output current is 49A. How much power is produced by the promary coil?
600W