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Chapter 17.2 – Current electrical potential energy –

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Presentation on theme: "Chapter 17.2 – Current electrical potential energy –"— Presentation transcript:

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

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