The resistance of each brake lightbulb on an automobile is 7.0 Ω.

Question

The resistance of each brake lightbulb on an automobile is 7.0 Ω.

Cars have 12-V electrical systems to compute the current that flows in each bulb if they are connected in series. (For simplicity, assume that the circuit is only composed of one brake lightbulb and the car battery.)

Answer 1

Hello! Please refer to my other post regarding electric circuits for a detailed summary of basic electricity.

Here, we have a problem dealing with voltage. Voltage ( V ) describes a quantity of energy deposited in circuit elements when a coulomb of charges passes through the element or elements ( Joules per coulomb, or J/C ). In this case, we have a single resistor ( the light bulb ) in the circuit; Therefore if the battery voltage provides 12 Joules ( J ) of energy per coulomb ( C ) of charge released into the circuit, The resistor ( R ) will experience an energy drop ( Voltage drop ) of 12 Joules each time it resists the passage of 1 Coulomb of charge. Therefore, the voltage drop across the resistor = 12 V.

The basic equation for Voltage ( V ) = IR, where V is in units of Joules per Coulomb ( J/C ), I is equal to the magnitude of the current in Amperes ( C / s ), in resistance ( R ) is in units called Ohms. Therefore, the current flowing through the bulb is equal to ( V / R ) = I.

( 12 V / 7 ohms ) = 1.7 A ( Amperes ).