Chapter 23 - Electric Current

10. What is the unit of electrical resistance?

Ω Ohm

4. What exactly is an Ampere?

1 Ampere = 1 Coulomb of charge per 1 second Amps= current

6. How much energy is supplied to each Coulomb of charge that flows thru a 12-V battery?

12-JOULES are supplied to each Coulomb

2. What condition is necessary for the sustained flow of water in a pipe? What analogous condition is necessary for the sustained flow of charge in a wire?

A continuous flow of water is possible if the difference in water levels within a container (difference in water pressures) is maintained via the use of a water pump Likewise, to attain a sustained flow of charge in a wire some arrangement must be made to maintain a difference potential in the wire while charge flows from one end to the other continuously.

57. What condition is necessary for the sustained flow of electric charge through a conducting medium?

A sustained flow of electric charge requires a sustained difference in electric potential across a conducting medium. This can be a battery or a generator

3. Why are electrons rather than protons the principal charge carriers in metal wires?

Because electrons in metals are free to wander around the atom, whereas protons are embedded in the atomic nucleus and cannot roam.

75. Only a small percentage of electrical energy fed into a common light-bulb is transformed into light. What happens to the rest of the energy?

More than 90% of electrical energy in an incandescent lamp goes directly to heat. Thermal energy is the graveyard of electrical energy.

39. Calculate the current in the 240 Ω filament of a bulb that is connected to a 120-V line

Ohm's law: Amps=V/Ω so: 120/240= 0.5A

38. When you touch your fingers (resistance 1000Ω) to the terminals of a 6-V battery, show that the current moving through fingers is 0.006 A

Ohm's law: Amps=V/Ω so: 6/1000= 0.006 A

40. An electric toy draws 0.5A from a 120-V outlet. Show that the toy consumes 60-Watts of power.

Ohm's law: Watts=A*V so: 0.5*120= 60W

14. What is the function of the round third prong in a modern household's electrical plug?

The third prong connects to a ground/a wire that is grounded to prevent accidental shock

13. How does wetness affect the electrical resistance of your body?

Wetness LOWERS electrical resistance

58. What two things can be done to increase the amount of flow in a water pipe? Similarly, what two things can be done to increase the current flow in an electric circuit?

a). To increase the amount of water flow in a pipe you can increase the pressure of the water and increase the diameter (width) of the pipe b). To increase the flow of current in a circuit you can increase the Voltage & increase the diameter of the wire

1. What condition is necessary for the flow of heat? What analogous condition is necessary for the flow of charge?

a). When conducting materials are at different temperatures, there is a difference potential present, and heat will flow from hot to cold. b). Likewise, when the ends of electric conductors are at different electric potentials, charge will flow from one end to the other. WITHOUT a potential difference NO CHARGE WILL FLOW