1. Chapter 17.2 – Current electrical potential energy –
the ability to move an electric charge from one point to another
for like charges, potential increases as charges move closer
for unlike charges, potential decreases as charges move closer

2. Chapter 17.2 – Current potential difference –
the change in electrical potential energy divided by the charge that moves through the electric field
measured in units of volts (V)
often called voltage
outlets have a voltage of 120 V

3. Chapter 17.2 – Current Batteries
the ends of a battery are called terminals
there is a potential difference between terminals of a battery
batteries are made of electrochemical cells – devices that convert chemical energy to electrical energy
the cells contain an electrolyte – a solution that conducts electricity
each cell has 2 electrodes – a conductor used to make contact with the electrolyte

4. Chapter 17.2 – Current there are 2 kinds of batteries dry cell –
has a moist pastelike electrolyte
typically 1.5 V
ex. AA, AAA batteries, cell phone & laptop batteries
wet cell –
has a liquid electrolyte
typically 12 V
ex. car battery

5. Chapter 17.2 – Current electric current –
rate at which charges pass through a given point or conductor
measured in amperes (A)
batteries produce a current by creating a potential difference across an electrical device
the electric field pushes electrons toward the side with lower potential

6. Chapter 17.2 – Current
direct current (DC) – electrons always move from one terminal to the other in the same direction ex. batteries alternating current (AC) – electrons constantly change direction between terminals ex. wall socket

7. Chapter 17.2 – Current conventional current –
current made of positive charge that has the same effect as the actual motion of charge
the direction of conventional current is opposite the direction that electrons move
resistance –
opposition to the movement of a current by a material or device
caused by internal friction which slows the movement of charges
units of ohms (Ω)

8. Chapter 17.2 – Current resistance can be found from Ohm’s law
𝑟𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒= 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 𝑅= 𝑉 𝐼
another way is to write V = IR
units: volts = amps ∙ ohms
ex. Find the resistance of a lantern that uses a 24 V power supply and draws a current of 0.80 A.

9. Chapter 17.2 – Current
The current in a resistor is 0.50 A when connected across a voltage of 120 V. What is the resistance of the resistor? A 1.5 V battery is connected to a light bulb with a resistance of 3.5 Ω. What is the current in the bulb?

10. Chapter 17.2 – Current conductors have a low resistance
insulators have a high resistance
semiconductor –
has properties between conductors and insulators
ex. used in computers, cell phones, anything with a microchip
superconductor –
material with zero resistance when their temperature falls below a critical temperature
very cold temperatures (-272°C to -123°C) are used to make powerful magnets to levitate trains

11. Chapter 17.2 – Current
ground wire – wire connected to the ground which carries excess charge to the ground where it spreads out safely ex. third prong on power outlets

12. Chapter 17.2 – Current