Current and Circuits test

What is a current? What is it measured in?

The rate of flow of electrical charge

Unit: Amps (A)

What is necessary for a current to begin to flow? What must you connect to a circuit?

In order for a current to flow, the circuit must be closed. A power source must be connected to a circuit.

What are the two sources of electric current? How do batteries and generators work?

Batteries and generators supply energy to charge carriers. They set up a potential difference across the circuit.

Batteries: convert chemical PE to electrical PE

Generators: convert mechanical energy to electrical PE

Which direction do charges always move?

negative to positive

What is resistance? What is it measured in?

opposition to the flow of current in a conductor (electrical current)

Unit: Ohms (Ω)

What is a resistor?

a component put in a circuit to control (slow) the flow of the current

What is a superconductor?

materials that have a resistance of zero at or below critical temperatures (perfect conductors)

What are the four factors that determine how much resistance a resistor has?

Length, Thickness, Conductivity, and Temperature

What is Ohm's Law? What formula do we get from this law?

Def: For most conductors, the amount of resistance remains constant

Formula: V=IR

How is current related to the amount of resistance in a circuit?

Current is INVERSELY proportional to the resistance of the conductor

How is current related to the amount of voltage in a circuit?

Current is DIRECTLY proportional to the voltage supplies to the source

What is power? What is it measured in?

the rate of which electric energy is converted from one form to another

Unit: Watts (W)

What is energy? What is it measured in?

the ability to do work (joules)

What is a circuit?

A complete path (loop) which charge can flow

What must all circuits consist of in order for charges to flow in a current?

A battery

What is the name for the diagrams we use to draw circuits?

schematic diagrams

How do you connect a voltmeter to a circuit? How do you connect an ammeter? What do these devices measure?

Voltmeter- connect one end to one terminal (voltage)

Ammeter- place it on the wire (current)

Series Circuit-

Def: one loop for current flow through

• elements are connected end to end

• current is constant

• voltage is divided

Parallel circuit-

Def: Resistors are connected such that there are multiple pathways for electrons to flow, and multiple currents flow through the circuit.

• elements are connected side by side

• current is divided

• voltage is constant