Why doesn't electricity just flow out of a wire into the air around it? Try to explain using scientific terms.

Electric Current ReviewWhich of the signs below would indicate the most danger?

A B C

D E

A) “A” B) “B” C) “C” D) “D” E) “E”

DANGER!HIGH RESISTANCE

1,000,000 Ω

DANGER!HIGH VOLTAGE

1,000,000 V

DANGER!HIGH CURRENT

1,000,000 A

DANGER!HIGH ELECTRIC

POTENTIAL

DANGER!HIGH ELECTRIC

FIELD

Electric Current ReviewHow does a battery work?

A) It pulls protons from a large negative charge and puts them back on a large positive charge.

B) It pulls protons from a large positive charge and puts them back on a large negative charge.

C) It pulls electrons from a large negative charge and puts them back on a large positive charge.

D) It pulls electrons from a large positive charge and puts them back on a large negative charge.

E) None of the above explain how a battery works.

Electric Current ReviewWhy does a circuit stop conducting when you cut the wire?

A) The current of the circuit becomes infinite.

B) The current of the circuit becomes zero.

C) The resistance of the circuit becomes infinite.

D) The resistance of the circuit becomes zero.

E) The voltage of the circuit becomes infinite.

Electric Current ReviewWhy don’t birds get electrocuted when they stand on power lines?

A) They don’t offer a potential difference for the current.

B) Birds do get electrocuted. They’re just really tough.

C) Current only flows through metal and birds aren’t metal.

D) Their resistance is too high for the current to flow.

E) Electricity doesn’t actually move through power lines.

Electric Current ReviewWhy can dropping a plugged-in toaster in the bathtub kill you?

A) Electricity keeps flowing out of the toaster until the water is “full”.

B) Electrons in the toaster combine with those in the water to get high current.

C) When skin is wet, resistance goes down, so the current increases.

D) It can’t kill you. There’s just not enough electricity to kill.

E) The current heats up the water super fast and you burn to death.

Electric Current Practice Problems1) Why are electrons, rather than protons, the principal charge

carriers in metal wires?

2) Calculate the current in a toaster that has a heating element of 15 Ω when connected to a 120 V outlet.

3) Calculate the current that moves through your fingers (resistance 1000 Ω when you touch them to the terminals of a 6 V battery.

4) If 10 A of current pass through a 90 Ω heating element, what’s the voltage through the circuit?

5) Consider a circuit with a main wire that branches in two. If the current is 9 A before the split, what is the current in each branch if one branch is twice as thick as the other?

A 1-mile long copper wire has a resistance of 10 Ω. What will be it’s new resistance when it is shortened by cutting it in half?

What if we just fold it over in half to get the same amount of wire in half the distance?

Does an electrical wire have an overall positive or negative charge? Explain your answer.

classwork

Exit Question #11

Imagine we have a gap in a wire like shown below. What can we say about the point where we have the gap?

a) the current is zero

b) the current is infinite

c) the resistance is zero

d) the resistance is infinite

e) “B” and “C”

f) “A” and “D”