4.0 PAT review

Question 1

What is the difference between static and current electricity? Give an example of each.

Answer 1

Current is the constant flow of electrons along a specific path. Example: wires from IPod.

Static is a quick burst of built-up electrons. Example: clothes out of the dryer.

Question 2

What makes electricity more dangerous, its voltage or current?

Answer 2

Current (amperes).

Question 3

What level of current can kill you?

Answer 3

0.1 amp can be fatal.

Question 4

What is a short circuit?

Answer 4

An unintended path for electricity that bypasses the ‘normal’ circuit.

Question 5

What are some safe and unsafe practices around electricity?

Answer 5

Unsafe: Overloading, electronics near water, using frayed cords, misuse of plugs, pulling on cord, removing ground plug etc.

Safe: adhere to warning signs, where appropriate safety gear, don’t bypass safety features, unplug when servicing etc.

Question 6

What is the difference between conductor, insulator and superconductor?

Answer 6

Conductor: a material that an electrical charge can easily move through.
Insulator: a material that an electrical charge can NOT easily move through.
Superconductor: a material that offer absolutely zero resistance to electrical flow; a perfect conductor.

Question 7

Define a Wet Cell and give an example.

Answer 7

an electrochemical primary cell having LIQUID electrolytes (car batteries).

Question 8

Define a Dry Cell and give an example.

Answer 8

an electrochemical primary cell having PASTE electrolytes (common batteries).

Question 9

Define a Primary Cell and give an example.

Answer 9

Produce electrical reactions that CANNOT be reversed (Energizer AAA’s).

Question 10

Define a Secondary Cell and give an example.

Answer 10

Produce electrical reactions that CAN be reversed with the introduction of an electrical charge (cell phones).

Question 11

What is a resistor? What factors can increase the resistance in a wire?

Answer 11

A device used to restrict the flow of electricity (Ohms).

Factors: length, cross-section, temperature, material.

Question 12

Use Ohm’s Law (V=IR) to solve the following. A student measures the current in a circuit to be 0.50A. The circuit has one light bulb in it with a resistance of 10 Ω. What is the voltage in the circuit?

Answer 12

V=5 volts

Question 13

Use Ohm’s Law (V=IR) to solve the following. A fire truck has a searchlight with a resistance of 60 Ω and uses a 24 V battery. What is the current in this circuit?

Answer 13

I= 0.4 amps

Question 14

Draw a series circuit with a three-cell battery, two motors, one light bulb and a switch.

Answer 14

3 batteries, 2 motors, 1 light and a switch.

Question 15

Explain what you are measuring with a Galvanometer, Ammeter, Ohmmeter, Voltmeter?

Answer 15

• measures small currents
• measures electrical currents
• measures resistance
• measures the voltage difference across a circuit

Question 16

What is Mechanical Energy?

Answer 16

The energy possessed by an object because of its motion or potential to move (a shot hockey puck)

Question 17

What is Chemical Energy?

Answer 17

The energy stored in chemicals that is released when the chemicals react (battery acid).

Question 18

What is Thermal Energy?

Answer 18

The total kinetic energy of a substance released when particles move faster (boiling water vs tap water).

Question 19

What is the difference between a motor and generator? (Include energy conversions that occur)

Answer 19

Motor: needs energy to operate

Generate : converts energy to electrical currents

Question 20

What is the difference between AC and DC current?

Answer 20

DC – electricity flows in only one direction

AC – electricity flows back and forth 60 times per second

Question 21

Using the following formulas to solve the following:
P = IV Energy = Power x time Efficiency =
Useful output/Total input x 100%
A hair dryer has a power rating of 1000W. If it is plugged into a 120V outlet, what is the current flowing through the device?

Answer 21

1000 = I x 120
I = 1000/120
I= 8.3 amps

Question 22

Using the following formulas to solve the following:
P = IV Energy = Power x time Efficiency =
Useful output/Total input x 100%
If you cook a roast in a microwave (P = 800W) for 30 min, how many joules of energy are being converted to heat by the microwave?

Answer 22

E = 800  x (60 x 30)
E = 800 x  1800
E = 1 440 000 Joules (1.4 MJ)

Question 23

Can you have a 100% efficient appliance? How can you improve the efficiency of a device?

Answer 23

No appliance is 100% efficient.

Limited the heat loss and friction.

Question 24

Explain how the following power plant Thermoelectric Coal Burning generate electricity for our homes and describe one positive and one negative effect.

Answer 24

Converts chemical energy stored in coal to thermal energy, then kinetic energy, finally to electric energy.
Positive: relatively inexpensive to use, in Canada ample supply
Negative: Combustion creates CO2 and SO2 (global warming), limited supply drastic impact on environment

Question 25

Explain how the following power plant Thermonuclear generate electricity for our homes and describe one positive and one negative effect.

Answer 25

Nuclear fission occurs releasing vast amount of energy used to produce steam to run turbines, which in turn power up generators to produce electricity.
Positive: endless potential energy. Clean burning
Negative: poor public image. Radioactive by products last for centuries.

Question 26

Explain how the following power plant Hydro-electric generate electricity for our homes and describe one positive and one negative effect.

Answer 26

Water is run under high pressure to run a turbine which powers a generator to produce electricity.
Positive: clean as far as air and water pollution is concerned, efficient.
Negative: huge physical impact in construction of the dams needed.

Question 27

Define the Renewable Resources and give an examples.

Answer 27

A resource that can be replenished naturally within 100 years.

• Solar
• Geothermal
• Wind
• Biomass
• tidal

Question 28

Define Non-renewable resources and give an example.

Answer 28

A resource that CANNOT be replenished

• coal
• fossil fuels