Warm-up Activity

1
Warm-up Activity

• Think about your experience with the PhET circuit
  simulation that you recently completed
• Record in your notebook
• Two things that you enjoyed/learned from the lab
• One thing that you feel you didnt understand
• Discuss your responses with your group members

2
Electrical Power Energy
3
Electrical Energy

• Most electrical energy is produced from natural
  resources and provided to our homes by Electrical
  Utility Companies.

4
How does the electrical company produce energy?
5
Circuits(energy transformation tools)

• Circuits are a way to convert electrical energy
  into energy we need such as heat and light.

6
Electrical Power

• The rate at which the electrical energy is
  converted into useful energy such as heat or
  light (depends on the device).

This light bulb takes 60 Joules of energy from
the circuit every second!
This light bulb takes 100 Joules of energy from
the circuit every second!
60 Watts
100 Watts
7
Electrical Power

• P IV

Power (Watts)
Voltage (Volts)
Current (Amps)
8
Example

• A lamp operates with a current of .83 A and a
  potential difference of 120 V. How much power
  does the lamp use?

9
Electrical Energy

• Amount of energy used depends upon power
  requirements by appliances and how long they are
  used

E Pt
Energy (kWh) (J)
Power (kW) (W)
Time (hrs) (s)
10
Household Circuits

• Standard voltage in U.S. 120V
• Main switch and circuit breaker box serve as
  electrical headquarters for your home
• Many appliances can draw current from the same
  circuit. A fuse or circuit breaker is wired in
  between each parallel circuit.

11
Electrical Energy Problem

• A 60 W lightbulb is left on for 8.5 hours.
  How many kWh of energy are used? How many Joules
  of energy are used?

12

• Assume Xcel energy charges .10 per kWh (or
  per 3,600,000 Joules). How much would it cost to
  run the lightbulb in the previous question for
  one week (assuming it was on 8.5 hrs/day)

13
Electrical Safety

• Correct wiring, fuses, circuit breakers,
  insulation and grounded plugs help make
  electrical energy safe

14
Energy in your home

• Draw on your personal experiences to calculate
  your familys energy usage!
• Think of a normal week when all members of your
  family are home
• Determine how many hours each appliance is
  actually used
• If there is more than one of the same type of
  appliance in your house, count all of them toward
  your total!

15
A scent plug in uses 120 V of potential
difference and a current of 1.1. A to operate.
How much power is the scent plug-in using?

1. 109.1 W
2. 132 W
3. 121.1 W
4. Not enough information

16
If the scent plug in has a power rating of 132 W,
what is the power in kW?

1. 132000 kW
2. 13.2 kW
3. 0.132 kW
4. 0.000132 kW

17
If the scent plug in uses 0.132 kW of power and
is plugged in at all times, how many
kilowatt-hours of Energy are used in 1 week?

1. 22.18 kWh
2. 3.168 kWh
3. 1272.7 kWh
4. Less than 1 kWh

18
If the energy company charges 0.10 for every kWh
of energy used, how much would you be chared for
22.18 kWh of usage?

1. 0.79
2. 1.50
3. 221.80
4. 2.22

19
Are the Vikings going to beat the Packers
tomorrow?

1. Definitely
2. Yes
3. Most Definitely
4. No
5. Guaranteed
6. Yes