4.0 PAT review Flashcards
(28 cards)
What is the difference between static and current electricity? Give an example of each.
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.
What makes electricity more dangerous, its voltage or current?
Current (amperes).
What level of current can kill you?
0.1 amp can be fatal.
What is a short circuit?
An unintended path for electricity that bypasses the ‘normal’ circuit.
What are some safe and unsafe practices around electricity?
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.
What is the difference between conductor, insulator and superconductor?
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.
Define a Wet Cell and give an example.
an electrochemical primary cell having LIQUID electrolytes (car batteries).
Define a Dry Cell and give an example.
an electrochemical primary cell having PASTE electrolytes (common batteries).
Define a Primary Cell and give an example.
Produce electrical reactions that CANNOT be reversed (Energizer AAA’s).
Define a Secondary Cell and give an example.
Produce electrical reactions that CAN be reversed with the introduction of an electrical charge (cell phones).
What is a resistor? What factors can increase the resistance in a wire?
A device used to restrict the flow of electricity (Ohms).
Factors: length, cross-section, temperature, material.
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?
V=5 volts
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?
I= 0.4 amps
Draw a series circuit with a three-cell battery, two motors, one light bulb and a switch.
3 batteries, 2 motors, 1 light and a switch.
Explain what you are measuring with a Galvanometer, Ammeter, Ohmmeter, Voltmeter?
- measures small currents
- measures electrical currents
- measures resistance
- measures the voltage difference across a circuit
What is Mechanical Energy?
The energy possessed by an object because of its motion or potential to move (a shot hockey puck)
What is Chemical Energy?
The energy stored in chemicals that is released when the chemicals react (battery acid).
What is Thermal Energy?
The total kinetic energy of a substance released when particles move faster (boiling water vs tap water).
What is the difference between a motor and generator? (Include energy conversions that occur)
Motor: needs energy to operate
Generate : converts energy to electrical currents
What is the difference between AC and DC current?
DC – electricity flows in only one direction
AC – electricity flows back and forth 60 times per second
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?
1000 = I x 120 I = 1000/120 I= 8.3 amps
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?
E = 800 x (60 x 30) E = 800 x 1800 E = 1 440 000 Joules (1.4 MJ)
Can you have a 100% efficient appliance? How can you improve the efficiency of a device?
No appliance is 100% efficient.
Limited the heat loss and friction.
Explain how the following power plant Thermoelectric Coal Burning generate electricity for our homes and describe one positive and one negative effect.
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
