Electric Force = the force of attraction or repulsion between object due to charge. Electric Force depends on charge and _______________.
Voltage and Current! Volt is the SI unit for potential difference. (voltage) (V) A cell is a source of electrical current because of the potential difference, or voltage, between the terminals. A voltage sets a charge in motion. ◦Example: Electrons move from the negative terminal of a battery to the positive terminal when a flash is turned on.
Current is the rate that electric charges move through a conductor. ◦Measured in Amperes (A) ◦SI unit I
*Conductors have low resistance* Resistance is the ratio of voltage across a conductor to the current it carries. Resistance is caused by internal friction and slows the movement of charges. Resistance = Voltage/Current
Practice problems The heating element in an electric kettle has a resistance of 30 Ω. What is the current in the heating element when it is connected to a 230 V supply?
A circuit contains a 6 volt battery and a bulb with a resistance of 3 ohms. Calculate the current. What is the voltage of a circuit with 15 amps of current and toaster with 8 ohms of resistance?
A circuit contains two 1.5 volt batteries and a bulb with a resistance of 3 ohms. Calculate the current. You have a large flashlight that takes 6 D- cell batteries. If the current in the flashlight is 2 amps, what is the resistance of the light bulb? (Hint: A D-cell battery has 1.5 volts.)__________________