PY 131 Module 18 - Electric Current

How does charge flow within a circuit?

From higher to lower electric potential

How fast do electric Fields move?

The speed of light

The battery works as a..

An electric potential pump

What is the drift speed in an electric current

About 0.33 m per hour

What is one voltage?

1 joule of Energy/1 coulomb of charge

Voltage can be thought of as an electrical..

Pressure

Formulae for current

Current= voltage difference/resistance

(^ Ohm’s Law)

Current= flow of charge/second

High voltage only means a lot of current if the..

Resistance is low

What does resistance do

It resists the flow of charge. It's sign is omega

State Ohm’s Law

Current (I) = Voltage (V)/Resistance (R)

The current in an electric bulb depends upon the..

Voltage across the bulb divided by the filament resistance

It is best to say that voltage is established across a bulb and charge flows …

Through a filament

Within a direct current, the current flows..

In One Direction

Within an alternating current, the current flows…

Back and forth

AC ______ voltages, which results in the transmission of electricity along _____ distances with _______ heat loss

Steps up and steps down

Long distances

Minimal heat loss

DC results in _____ transmission distances and _____ heat loss

Shorter transmission

Greater heat loss

The North American Standard consumer voltage is at about ___ volts which is ____ efficient than ___ volts

120 v

Less efficient

220 v

Where do the electrons in an electronic circuit come from?

From the materials that make up the wires themselves

What is drift speed

How fast electrons move in a typical electric circuit— Very slow 🐌

How fast is the electric field

The speed of light

Energy in an electric circuit formula

Energy = charge × voltage

Power in an electric circuit formulae

Power=(current)(Voltage) → P=IV

Power=Voltage²/Rsistance →P=V²/R

Power=(current²)(Resistance) → P=I²R

What is 1 Watt?

1 watt= (1 amp)(1 volt)

As you add more light bulbs in series the voltage across the two terminals of a battery…

Stays the same

As you add more light bulbs in series the voltage across each light bulb…

Decreases

As you connect more light bulbs in parallel the resistance experienced by a battery…

Decreases

Where do the electrons that light up an incandescent lamp come from within an AC circuit?

The atoms in the light bulb filament

What flows through a circuit?

Charge flows in a closed circuit

How much power dissipates in a 2 ohm line carrying 80 amps of

12,800 Watts

What Smooths out electric pulses

Capacitors

What is the normal charge on a wire carrying an electric current?

There's no charge at all

What sort of current do you get when you plug a 60 W light bulb into a 120 volt circuit?

0.5 amps

What do we really mean when we say that a kitchen appliance uses up electricity?

Electron kinetic energy is changed into heat

What power dissipates as 3 amps crosses a 4 ohm resistor?

P=I²R

P=(3²)(4) = 36 W

36 Watts

What happens to be electric field within an AC circuit

It changes magnitude and Direction with time

When connected in series, which is greater? Current in the the thick lamp filament or the thin lamp filament?

The current is the same in each lamp

When a thick lamp filament and a thin lamp filament are connected in parallel which has the greater voltage drop?

The drop across each lamp is the same

How is an alternating current normally produced

Buy a generator

A man gets shocked electrically but where did the electrons shocking the man come from?

The man's body

What happens to the resistance of a copper wire after being stretched thinner

Electrical resistance increases

What electrical device does the circuit breaker substitute for

A fuse

When you add another lamp to a parallel circuit what happens to the overall current

It increases

How does the charge flow in a circuit powered by a battery?

Through both the battery and the rest of the circuit

How are the radio fan and headlights of car connected electrically

In parallel with a switch for each

What happens to the current within a power source as more lamps are attached in a series circuit

The current decreases

Which has a greater resistance of 50 watt light bulb or 100 watt light bulb if both are rated at 110 volts

The 50 watt light bulb

What gives the energy to the moving charges in a light bulb circuit

A generator

When adding another lamp to a series circuit what happens to the overall current

The current decreases

What causes electrons to flow within a wire

A potential difference across the ends

What does the capacitor store

Within a circuit a 120 volt potentials applied across a 10 ohm resistor. What current is flowing through the resistor

12 amps

How is an electrode diode useful

For changing AC to DC

How does the thickness of a 100 watt light bulb compared to that of a 60 watt light bulb

The 100 watt light bulb has a thicker filament

What happens in a 120 volt circuit with a lamp in series?

120 joules of energy are given up by each coulomb of charge making up the current in the circuit

What happens to the electrical resistance in a copper wire as it is heated

Electrical resistance increases

What is the combined resistance of a 4 ohm and 6 Ohm resistor connected in parallel

2.4 ohms

When a thick lamp filament and a thin lamp filament are connected in series Which experiences the greatest drop in voltage

The thin filament lamp experiences the greater drop

What is the combined resistance of two 1 ohm resistors in series and in parallel

2 ohms in series and 1/2 ohm in parallel

Lamp in a circuit carrying two amps attached to a 120 voltage source has how much electric power

240 Watts

Must a wire be charged to carry an electric current

It may or may not be electrically charged

When a thick lamb filament and a thin lamp filament are connected in parallel Which experiences the greatest current

There is greater current in the lamp with a thick filament

How does it compare when two resistors are placed in series versus when two resistors are placed in parallel

In parallel there is less resistance

What kind of current will you get in a toaster designed for 110 volts when plugged into a 220 volt Outlet

The current will be twice what it should be

What electrical resistance does a battery experience when the two lamps of the circuit are connected in parallel

Less than the resistance of either lamp

Which has higher electrical resistance a 100 watt light bulb or a 50-watt light bulb

50 W light bulb has a higher resistance

What happens to the current within a power sources more lamps are attached in a parallel circuit

The current increases

What electrical resistance does a battery experience when connected to two lamps in series

More than the resistance of either lamp

To identical light bulbs in a series circuit draw a current of 0.25 amps while there is a 110 voltage across both bulbs. What is the resistance of each bulb

220 ohms

How many 300 watt electric hair dryers can be safely hooked up to a 110 volt circuit designed to accommodate no more than 15 amps?

Five

As more lamps are put into a parallel circuit the overall current in the power source…

Increases