Chapter 7 Electricity

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3 Ω

A 0.7 ohm, a 1.5 ohm, and a 0.8 ohm resistor are connected in series across a 90 V battery. What is the resistance of the entire circuit?

3 A

A 10 ohm, a 15 ohm, and a 5 ohm resistor are connected in series across a 90 V battery. What is the current of the entire circuit?

150 Ω

Find the resistance of an electric light bulb if there is a current of 0.8 A and a potential difference of 120 V.

6.3 A

What is the current through an electric heater with a resistance of 38 ohms when the potential difference is 240 V?

series circuit

current has only one loop to flow through

The meter reading for June was 84502 kWh, & on July the meter read 87498. If the cost of electricity was $0.12 per kWh . What was the electric bill for June ?

...$359.52

What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it?

1 volt

What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?

1.5 amperes

What is the current flowing through a 24-ohm resistor connected across 240 volts?

10 amperes

What is the voltage across a 10-ohm resistor if a current of 1 ampere flows through it?

10 volts

How many times a second does lightning strike the Earth?

100

What is the current flowing through a 100-ohm resistor connected across 200 volts?

2 amperes

What is the voltage across a 10-ohm resistor if a current of 2 amperes flows through it?

20 volts

What is the resistance of a circuit that draws 4 amperes from a 12-volt source?

3 ohms

What is the resistance of a circuit in which a current of 3 amperes flows through a resistor connected to 90 volts?

30 ohms

What is the resistance in a circuit for which the applied voltage is 12 volts and the current flow is 1.5 amperes?

8 ohms

30 A

A 0.7 ohm, a 1.5 ohm, and a 0.8 ohm resistor are connected in series across a 90 V battery. What is the current of the entire circuit?

30 Ω

A 10 ohm, a 15 ohm, and a 5 ohm resistor are connected in series across a 90 V battery. What is the resistance of the entire circuit?

96 V

A 120 ohm resistor has 0.8 A of current flowing through it. Calculate the voltage.

150 V

A 75 ohm resistor has 2A of current flowing through it. Calculate the voltage.

dry cell batteries

A cell consists of two electrodes surrounded by a material called an electrolyte

104.2 V

A circuit with 4 A flowing through it has a 26.05 ohm resistor attached to it. How much voltage much power the circuit?

120 W

A laptop draws 2 A of current when connected to a 120 volt circuit. Calculate its power.

60 Ω

A laptop draws 2 A of current when connected to a 120 volt circuit. Calculate its resistance.

conductor

A material in which electrons are able to move easily

circuit breaker

A reusable safety switch that breaks the circuit when the current becomes too high

60 W

An alarm clock draws 0.5 A of current when connected to a 120 volt circuit. Calculate its power.

240 Ω

An alarm clock draws 0.5 A of current when connected to a 120 volt circuit. Calculate its resistance.

Lead-acid batteries

Contains a series of six wet cells made up of lead and lead dioxide plates in a sulfuric acid solution

How much will it cost to run the TV if the cost of energy is $0.10 per kWh ?

Cost = kWh * Hours Cost=.55 * $0.10 * 1 hour Cost = $0.06

How much will it cost to run the TV if the cost of energy is $0.10 per kWh ?

Cost = kWh * Hours Cost=4.4 kWh * $0.10 * 1 hour Cost = $0.44

TV operates 5 amps on a 110 volt circuit for one hour. Calculate kWh

Determine Power: P=V * I P=110 volts*5 amps P=550 watts Convert watts to kW : 550 watts * (1kw / 1,000 watts) 0.55 kW Multiply by hours .55kW * 1 hour = .55 kWh

TV operates 5 amps on a 110 volt circuit for one hour. Calculate kWh

Determine Power: P=V * I P=110 volts*5 amps P=550 watts Convert watts to kW : 550 watts * (1kw / 1,000 watts) 0.55 kW Multiply by hours: 0.55 kW * 1 hour = 0.55 kWh

TV operates 20 amps on a 220 volt circuit for one hour. Calculate kWh

Determine Power: P=V * I P=220 volts*20 amps P=4400 watts Convert watts to kW : 4400 watts * (1kw / 1,000 watts) 4.4 kW Multiply by hours: 4.4 kW * 1 hour = 4.4 kWh

96 Ω

Find the resistance of an electric light bulb if there is a current of 1.25 A and a potential difference of 120 V.

6.3 W

How much power is used by a 9V remote control that has a current of 0.7A?

What formula is used to calculate current in a circuit?

I = V / R

108 W

If a 40 V blender is supplied with 2.7 A of current, how much power will the blender have?

14.8 Ω

If a 40 V blender is supplied with 2.7 A of current, what amount of resistance will the blender have?

108 V

If a blender that has 40 ohms of resistance is supplied with 2.7 A of current, what amount of voltage will be used by the blender?

Electrons

Negatively charged particles

Protons

Positively charged particles

What formula is used to calculate resistance in a circuit?

R = V / I

True or False - All atoms are held together by electric forces between protons and electrons that are much larger than the gravitational forces between the atoms.

True

What formula is used to calculate voltage in a circuit?

V = I x R

E = electrical energy (kilowatt hour) kWh P = electric power (kilowatt) kW t = time (hours) h

What do letters in the electric energy equation represent?

150 W

What is the power of a 125 V appliance with 1.2 A flowing through it?

104.2 Ω

What is the resistance of a 125 V appliance with 1.2 A flowing through it?

6.3 V

What is the voltage needed to power a 1.26 A RC car with a resistance of 5 ohms?

What is lightning?

a large discharge of static electricity

insulator

a material that doesn't allow electrons to move through it easily

As the amount of charge on either object increases, the electrical force __________

also increases

law of conservation of charge

charge can be transferred from object to object but cant be created or destroyed

wet cell batteries

contains two connected plates made of different metals or metallic compounds in a conducting solution

parallel circuit

contains two or more branches for current to flow through

ohm's law

current in a circuit equals the voltage difference divided by the resistance.

The force between electric charges depends on

distance between charge; the force decreases as the charges get farther away

Which has less resistance, electrical conductors or insulators?

electrical conductors

Fuses

has a thin strip of metal that will melt if to much current flows through. -needs to be replaced once overloaded. -protects circuits from overheating.

The resistance of a conductor __________ as the conductor becomes longer and thinner.

increases

How is the electric resistance of materials related to the increase in temperature?

it increases as the temperature increases

What are ways to provide grounding?

lightning rods, plumbing fixtures

What are the best conductors?

metals

What are some good insulators?

plastics, wood, rubber, glass

Grounding

providing a path for electric charges to flow safely into the ground

voltage difference

push that causes charges to move and is measured in volts

electrical power

rate at which electrical energy is converted to another form of energy

charging by induction

rearrangement of electrons on a neutral object caused by a nearby change in induction

An electric field

surrounds every electric charge and exerts the force that causes other electric charges to be attracted or repelled

resistance

tendency for a material to oppose the flow of electrons changing the electrical energy into thermal energy and light

static electricity

the accumulation of excess electric charges on an object

What causes thunder?

the expansion and contraction of the air heated by lightning

charging by contact

the process of transferring charge by touching or rubbing

kilowatt-hour

unit of electrical energy

P = electric power (watts) W I = current (amperes) A V = voltage difference (volts) V

What do the letters in the electric power equation represent?

circuit

closed conducting path

An atom is electrically neutral because

the numbers of protons and electrons are equal


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