Science - Non-contact forces & electricity

What is static electricity?

A buildup of electric charge on a surface, usually caused by friction.

What device measures voltage?

A: Voltmeter (connected in parallel).

What device measures current?

Ammeter (connected in series).

What happens to current if voltage increases (and resistance stays the same)?

A: Current increases.

What happens to current if resistance increases (and voltage stays the same)?

Current decreases.

What is Ohm’s Law?

The relationship between voltage, current, and resistance:
V = I × R
(V = voltage, I = current, R = resistance).

What is resistance (R)?

A measure of how much a material resists the flow of current.

What is voltage (V)?

The energy per charge — the “push” that makes current flow.

What are insulators?

Materials that don’t allow electric charge to flow easily (e.g. rubber, plastic).

What are conductors?

Materials that let electric charge flow easily (e.g. copper, aluminum).

What is an electric current?

The flow of electric charge (electrons) through a conductor.

What are electric charges?

Positive (+) and negative (−) charges found in atoms (protons = +, electrons = −).

What is an electric force?

The force between charged objects — opposite charges attract, like charges repel.

What is magnetic force?

The force caused by magnets that can attract or repel other magnetic materials.

What is gravity?

A force of attraction between objects with mass.

Give three examples of non-contact forces.

Gravity, magnetic force, electrostatic (electric) force.

What is a non-contact force?

A force that acts without objects touching (e.g. gravity, magnetism, electric force).

What does V stand for?

Voltage

What is the unit for voltage?

volts/v

What does R stand for?

Resistance

What is resistance measured in?

ohms/Ω

What does I stand for?

Current

What is current measured in?

amperes/a

How to find I?

V ÷ R=I

How to find R?

V ÷ I=R

How to find V?

I × R=V

How to remember the 3?

triangle with V on top with I & R on the bottom

If a circuit has 12 V and 3 Ω resistance, what’s the current?

I = V ÷ R = 12 ÷ 3 = 4 A

If a circuit has 2 A current and 5 Ω resistance, what’s the voltage?

V = I × R= 2 × 5 = 10 V

If a circuit has 6 V and 2 A current, what’s the resistance?

R = V ÷ I = 6 ÷ 2 = 3 Ω