Voltage Sources

1
Voltage Sources
2
Household Circuits

• Standard household circuits are rated at 120 V
  and 15 A (12 A sustained load)
• Some devices, like electric dryers or ranges,
  require 240 V
• Some devices require a higher current rating,
  such as 20 A or 30 A circuit rating (each can
  take sustained loads of 75 of max rating
• How could a circuit be overloaded with too much
  current?
• How does a circuit breaker or fuse work?

3
(No Transcript)
4
Sample Question

• A current is overloaded and the circuit breaker
  breaks the circuit. Was the amount of resistance
  present too high or too low?
• Too low
• How many 100W light bulbs would it take to
  overload a standard American outlet?
• 15 light bulbs

5
Another question

• Annabelle is about to do her hair at a friends
  house. Her hair dryer is rated at 1875 W and her
  straightener is rated at 700 W. What should the
  current rating of the circuit be, at minimum?
• 30 A
• She notices that the circuit is a standard
  outlet. Should she use her devices?
• Dryer no
• Straightener yes

6
Question

• What is the maximum power that an electric range
  can dissipate on a 30 A circuit rated at 240 V?
• 5400 W

7
Batteries

• Modern battery (Voltaic pile) invented by Volta
  in 1800
• Term battery was coined by Franklin in
  similarities to a battery of guns
• Batteries convert electrochemical potential into
  electrical potential and current
• Primary batteries cannot be recharged while
  secondary batteries can

8
(No Transcript)