Charges
Which subatomic particle is able to "freely" move and why?
Electrons because they are in the orbital shell. The protons and neutrons cannot as they are confined in the nucleus.
What causes lightning?
Negative charges (electrons) at the bottom of the cloud are attracted to the positive charges (protons) in the ground
Conductor - Metals
Insulator - Rubber
What are the possible units for time in this unit that we have discussed? Hint: 2 different time measurements.
seconds or hours
An electric mower uses 1,620,000 J of energy in 1800 s it takes to mow the lawn. What is the mower's power?
Have to state the unit to get the point.
900 W
If an object loses electrons, what charge will it have? Why?
If an object loses electrons it will have a positive charge. This is because electrons are negatively charged, so if it loses a negatively charged electron, it is no longer neutral, therefore becoming positive.
What is a lightning rod do?
It helps transport the electric charge to the ground.
E in means the total energy, which is the energy that is being inputted in and will be transformed into another type of energy (useful and waste). Hint: will be the bigger value.
E out means the useful energy. Hint: will be the lower/smaller value
What are the units for Power and Energy?
Power is Watts (W)
Energy is Joules (J)
The power of a ceiling fan is 100 W. If the fan is on for 24 hours, how much energy is used?
Have to state the units to get the points.
8,640,000 J
Wool is closer to the top of the electrostatic series and has a weak hold on electrons, therefore it will _____ electrons and become ________ charged.
Lose
Positively
Why is it harder on a moist day to get a static shock?
Humidity makes the air more conductive, therefore the air can absorb and disperse any excess charges, hence making it harder for a charge to build up.
What will be the charge of rubber and hair when they are rubbed together.
Hair and rubber will initially start off as neutral and when they are rubbed together their charges will be:
Rubber - negative
Hair - positive
How do we convert from W to kW?
If a TV takes in 4500 J of electrical energy and only puts out 2000 J of sound and light energy, what is the TV's efficency?
Round answer to 1 decimal point.
44.4%
A positively charged object is grounded as the electrons travel from ______ to the _______
Ground to the object
Why is the car a safe place to be in a thunderstorm?
The car is made of metal, which means it is a good conductor. When lightning (discharge of electricity) hits your car, it is able to pass the flow of electricity through the car's metal frame to the tires to the ground.
Answers will vary.
What are the units for the following formula?
t = E/P
t = seconds (s)
E = Joules (J)
P = Watts (W)
A stereo uses about 0.040kW to run. If the current rate is 9.2 cents/kW*h, how much would it cost in cents to run a stereo for 10 hours in one day?
3.68 cents
If you have a positive charged object and a neutral object, what will happen?
Attract, repel or nothing?
Attract one another. This is because of the law of electric charges. Any charged object with a neutral object will result in attraction.
Why does our hair stand up when we touch the Van der Graaf generator?
The Van der Graaf generator is creating a build up of negative charges on the metal charge collector ball through the process of friction. When we put our hand on this metal ball, the negative charges pass through our hand, to our arm, to our hair. This results with a lot of negative charges in our hair, therefore causing the hair strands to start repelling one another as same charges repel.
Name one astronomical phenomenon, and explain the science behind it.
Answers will vary.
What are the units for the following values in this equation?
C = P x r x t
P = kW
r = dollar/kWh or cents/kWh
t = hours
A ceiling fan has a power rating of approximately 100W. If the fan is used for 4 hours a day, how much does it cost (in cents) to operate the fan for three weeks (21 days), if the rate is 10 cents/kW*h.
84 cents