Charge, Current and Voltage

Akoranga 11 Mahi Tuatahi

Take 10 minutes to continue working on the Education Perfect conductors and insulators task + making notes.

Any of the task left unfinished should be completed as homework.

Kahoot!

Ngā Whāinga Ako

1. Describe electric current in terms of a moving flow of charge (Coulombs per second)
2. Describe voltage in terms of the amount of electrical energy carried by each Coulomb of charge

Write the date and ngā whāinga ako in your book

Current (\(I\))

• In current electricity, charges have to flow through a conductor (e.g. copper wire).
• The charges that flow are electrons.
• These electrons carry a negative charge, and move from the negative to the positive terminal of the power supply.

• Current is given the letter \(I\) in equations, as it was historically known as intensité du courant (French).
• It is measured in a unit called Amperes (Amps) or A for short.
• It is measured by a ammeter which is placed in series in a circuit.

Pātai Tahi (Q1)

Discuss with the person next to you, why is it that negative charges flow, and positive charges do not? Write your conclusion down in your book.

Whakatika

• Electrons carry negative charge, and protons carry positive charge.
• In conductors, electrons are loosely held and can move freely throughout a solid in a “sea” of electrons.
• Protons cannot move, because they reside in the nucleus of the atom, and atoms are fixed in place.
• Electrons cannot flow easily or at all in insulators - this is why you stand on a chair with the Van der Graaf generator.

Charge (\(Q\))

• Each electron carries some amount of charge
• This charge is given the letter \(Q\)
• Charge is measured in a unit called a \(Coulomb\) (C).

Voltage (\(V\))

• At the negative terminal of a power supply, there are a large number of electrons present.
• Because they all have the same charge, they repel each other.
• This “pressure” to get away from each other is called Voltage
• As electrons pass through different components (bulb, resistor etc.) the voltage decreases.
• Components with a higher voltage are brighter/warmer
• The total voltage of the power supply must be “consumed”.

Pātai Rua (Q2): Calculate the Missing Voltage

Draw these diagrams into your book and label the missing voltages.

Ngohe/Task

1. Collect your sheet from the front
2. Cut out the pieces and the middle rectangle
3. Glue the big rectangle into your book
4. Match up the symbols next to the definitions and glue them in!
5. Place all un-crumpled excess paper into the green recycling bin!

Tūhura/Investigation: Current

1. In groups of 3-4 collect a light kit from the trolley and find a station around the room
2. Create a circuit with the power supply, two bulbs, and a switch in series.
3. Turn your circuit off, add an ammeter in series. Check with your teacher before you turn it back on!
4. What does the ammeter measure?
5. How does the reading change when you have 1 or 2 bulbs in the circuit?
6. How does changing the voltage impact your circuit?

Tūhura/Investigation: John Travoltage

1. Open the PhET Simulation on Google Classroom
2. Describe & explain what happens when you move his foot across the mat multiple times.
3. Describe & explain what happens when you bring his hand close to the door handle.
4. Investigate to see if there is a relationship between the amount of charge needed to cause a spark, and the distance of the hand to the door handle.