## 52 terms

### Current moves through a conductor at the speed of _____.

LIGHT: Approximately 186,000 miles per second.

### When you connect a D-C ammeter into a circuit you should always observe the correct _____.

POLARITY

### The law that defines the relationship between current, voltage and resistance is called _____ Law.

OHM'S LAW: If any two electrical characteristics are known, you can determine the third with Ohm's Law.

### According to Ohm's Law, the current in any circuit is _____ proportional to the applied voltage.

DIRECTLY

### Two meters that can measure electrical resistance are the _____ and _____.

OHMMETER & MEGOHMMETER: The ohmmeter measures circuit resistance; the megohmmeter measures the high resistance of insulation.

### Conductor

A material that gives up free electrons and offers only slight opposition to current flow.

### Free Electrons

Electrons in the outer orbits of an atom that can easily be forced out of their orbits.

### Insulator

A material that does not give up free electrons easily and offers opposition to current flow.

### Megohmmeter

An insulation-resistance tester. Consisting of a high-range ohmmeter and a high-voltage generator.

### Ohm

The basic unit of resistance measure. One ohm is equal to the resistance that allows 1 ampere of current to flow when an emf of 1 volt is applied.

### Voltage

The term most frequently used to express the difference of potential between two charges or between two points of a circuit.

### Voltmeter

A meter that is connected across the line to measure the potential difference (voltage) between two points.

### How should a voltmeter be connected in a circuit to measure voltage?

Across or in parallel with the potential points being measured.

### Without a given potential, how do free electrons in a conductor constantly move?

From negative to positive.

### Resistance

The property of a circuit which limits, opposes or resists the flow of electricity through it.

### The resistance of a conductor is measured in a unit called...

OHM: Named after the German physicist and mathematician George Simon Ohm.

### When the current (I) and resistance (R) are known, the voltage (E) can be found by the formula.

E = I x R

### When two points that have an electrical potential difference are joined by a conductor, _____ _____ results.

CURRENT FLOW

### The terms voltage and potential are both used to indicate the electrical _____ in a system.

PRESSURE

### In an electrical system, the potential is provided by a storage _____, a mechanically driven _____, or a dry cell.

BATTERY; GENERATOR

### An electrical current is produced when an applied voltage sets the free _____ of a material in motion.

ELECTRONS

### Materials that have few free electrons are called _____.

INSULATORS: Mica, porcelain, glass, bakelite and silicone are good insulating materials.

### If a battery is connected to teh two ends of a wire, the electrons movement in the wire is toward the _____ battery terminal.

POSITIVE