1. I. Current I is _________________________________________
Ex C of charge pass a point in 4.0 seconds. Find I.
I =
Units: coulomb/second = 1 _______________
1 C/s = 1 ____
So the answer can be written I = ________

2. Amperes are ______________________ units. (m___sk)
Coulombs are ______________________ units
What is a coulomb written in terms of fundamental units?
1 C =
Ex. How much charge passes a point if the current
at the point is __________ ampere for ________seconds?

3. Don't forget that the amount of charge Dq passing a
point can be written with units of __________________
or __________________________________ . The conversion
from one unit to the other is found on pg 1 of PhysRT:
1 C = _______________________ e
or 1 e = ________________________ C
Ex. How many electrons pass a point in 2.5 seconds if
the current at that point is 0.50 A?

4. To have current, you need _________________ 2 things:
___________________________ (aka ___________ source)
a/ a ______:
_________side or
_______ potential
_________side or
_______ potential
wire
wire
two _________________
The amount of ____________ depends on the metals used.
b/ a battery = _______________cell:
more cells  _________________
c/ a ______________ :

5. A voltage source V supplies ____________ to a circuit by
setting up ___________________________ within the circuit.
_______ pot.
_______ pot. V
flow of
___________
charge
flow of
________
( )
magnified wire
cross section
Electrons flow out of the ________________ side of V.
This is equivalent to flow of ___ charge out of ___ side of V.
The e-'s collide with _____________ of wire. This absorbs electrical __________________ and ______________ the wire.
The speed of e-'s ______________ collisions is ____________,
but the drift (________________) velocity of e- is __________ . .

6. Batteries supply a constant V  _____________ current
charge moves in
___________________ t
Generators supply a varying V  ________________ current
 ______ I
charge moves in _________________ t
charge moves in __________________
In Regents Physics, we will mostly study _____ ,
but the basic ideas are also valid for ______.

7. - 2. A ________________ circuit Using circuit symbols: Ex: +
Switch up  ___________ circuit  ________ current
Close the switch  ____________ circuit  _____________
 __________ flows  ______________
Can you have voltage without current?
Can you have current without voltage?

8. Current I is measured with an _________________, which
is often part of a DMM (______________________________ ).
Its symbol is:
In an electrical circuit, ammeters are connected
__________________ . This means the circuit must
be ________________ and the _______________ must
be _____________ into it:
Circuit _______ ammeter:
Circuit _________ ammeter:
circuit
part 1
circuit
part 1
circuit
part 2
circuit
part 3
circuit
part 2
circuit
part 3

9. Voltage V is measured with an _________________, which
is often part of a _________. Its symbol is:
In an electrical circuit, voltmeters are connected
__________________ . This means the circuit is _______
opened up , but the _______________ must be
connected _____________ two points in the circuit:
Circuit:
circuit
part 1
circuit
part 1
circuit
part 2
circuit
part 3
circuit
part 2
circuit
part 3

10. Ammeters measure the current that passes _________
a part of the circuit, in other words, the amount of
___________ each second that passes ____________ it.
Voltmeters measure the ________________________
from one side of a part of the circuit to the other side.
This is called the voltage _____________ the circuit part.
It represents the ____________ or _____________ needed to
force each ________________ of charge through.
In symbols:
Ideally, neither ammeter nor voltmeters ______________
________________________________ , but in reality they do.

11. II. Resistance R - __________________________________
____________________________________________________
_____________________________________________________
1. Resistance occurs as a result of ________________
colliding with ___________________ and with the
__________________________ , resulting in ____________ .
This converts __________________energy to ___________.
2. R is a __________________ . It has _________________ .
units of R: ___________________
It is a ______________________ unit.
3. Any factor that makes it more _________________for
_______________ to move will through a material will
__________________________________ of the material:

12. For _____________, there are four factors that affect
how much resistance it has:
A. __________________ R L
B. __________________ R A

13. Higher T  atoms of the metal _________________
temperature: R T
Higher T  atoms of the metal _________________
 ________________________ for e-'s
to move through the metal
 more ____________________
D. ______________________ : Different metals have different numbers of ____________________ .
 ______ electrons
 ______ current
 _______ resistance R
# of free electrons

14. These 4 factors are summed up in:
(rho) is called the _________________ of a material.
depends on the ___________________ of a metal
and is different for different _____________ .
units of r:
_________________
Lowest r = _______________
Highest r = _______________
Metals that have more free
_____________ will have a
_________ r and _________ R.

15. Ex. Calculate the resistance of 100 meters of copper
wire that has a cross-sectional area of 3.44 x 10-6 m2.
R = = =

16. A _________________is a device that is designed to
have a definite amount of _________________.
Resistors are used to
1. control _____________ flow; and
2. provide a _____________________
of a certain amount.
Symbols:
1. resistor:
2. variable resistor:

17. Two materials that do not follow these rules for metals
are _____________________ and ______________________ .
Semiconductors (like ___________ and ______________ )
have ____________ resistance at higher temperatures.
Here’s why:
___________ silicon (Si) is
an _______________________ .
It _____________ its outer e-’s
with 4 other silicon atoms in
a ___________________ bond,
so that its own electrons
_______________________
electricity.
= Si atom
= a ________ of
shared e-s

18. 3 4 5 C N Al Si Ge Phosphorus P and arsenic As
outer
e-’s 3 4 5 a t o m C N Al Si Ge
Phosphorus P and arsenic As
have __________ outer e- than Si.
Boron B and gallium Ga
If you add _________________ of P, As, B or Ga to pure Si, it creates extra charge carriers. This is called _____________ . Higher temps “free up” more of these extra charges and allows for more __________ and so less _____ . And because of the extra charge carriers,
semiconductors have _________________ resistances
that can be ______________ . They are now used in making almost all _______________________________ .

19. Superconductors:
The resistance R of superconductors is _________
as long as the material is _____________________________.
Because they have no _____ , electrons can travel through
them __________ , and so they can carry ________ currents
for _________________ without producing large amounts
of ___________ . This in useful in the ___________________
___________ and _________________________________________
Originally (around 1911), only certain ____________
were found to be superconducting. But they had to be
cooled to near ___________________ using liquid helium
(boiling point about _______ ) for this to happen.
This is very expensive.

20. In _______, a new type of superconductor was discovered whose makeup is similar to ________________ . These become superconductors at higher temperatures. This makes them much more ____________________.
Material
metal=m
ceramic=c
critical temp.
(K)
absolute zero
Zinc
0.88
Aluminum
1.19
Tin
3.72
Mercury
4.15
liquid nitrogen
YBa2Cu3O7 90
TlBaCaCuO
125
room temp.
293
much ___________
to use liquid N

21. III. Ohm's Law
Using R = rL/A, R can be found using the ____________________________of a metal wire.
In a circuit, R is defined for any device
as the ratio of __________________ the device to the
________________________the device:
A simple
circuit:

22. Ex. If the potential difference across a resistor is _______
and the current through it is __________, find R.
units: [ ] = [ ]/[ ] =

23. To remember all 3 equations, use:
V = ?
R = V / I
Solve this for
I = ?
To remember all 3 equations, use:
units: [V] = [I][R] =
[I] = [V]/[R]

24. Ex: What is the potential difference across a
25-W resistor when it carries a current of 3.0 A?
Ex: How much energy is required to make each coulomb
of charge pass through the above resistor?
Ex: What is the potential difference across a wire that
has no resistance?

25. 1. Assume the connecting wires have _________________
resistance. (They usually have ________________ R
than the circuit elements.)
For simple devices such as _______________________ ,
we often replace the device with the symbol for
__________________ : and assume that
it has all of the ______________________.
I = charge flowing _______________________________ .
The charge going __________ any circuit element must
_________ the charge __________ that element. Assume
____ charge flows out of the ____ side of the source.
V = potential difference __________________
= ____________________________ available to do work
= energy converted to _______________________ by R
= energy is __________________ by passing through R
= _________________________ across R
= _______ if there is no resistance, e.g. in a __________

26. Ex: A simple circuit has 1 _______. All of the __________________ is
dropped across the ___________,
because it is the only element in
the circuit that requires
____________ (voltage). V
source R
Graph the voltage drops as you follow ____________
charge from the _________ potential side of source, through
the _____________ , back to the _______ side of the source.
no V dropped in wire
b/c V = IR = ________ V
distance around the circuit

27. A simple circuit with ____________:
ammeter – measures current passing ____________ R
- Ideally, it has no ____, so no ________ across it
voltmeter – measures potential difference _________ R
- Ideally, it does not allow any ____ to enter it
The voltmeter must be connected
across _______________ sides of R
to measure potential _____________. R
Other ____________________ways to hook up the meters:

28. Remember:
V ____________ I  So changing V _______________ I.
Ohm’s Law: For __________________ conductors at
_______________ temp., I is ___________ prop. to V.
Case A: a device obeys Ohm’s Law  _____________ V I
slope = ΔV/ΔI = constant
so the ratio V/I = ____ is ___________
Case B: ________________ devices V I
 slope = V/I = R is ________________
In the case shown, R _______________
(Traditionally, V is plotted on the ____ axis)

29. Ex. If R is _____________ , then I is _____________ .
As R  ____, I  ____ . This is an ___________ circuit. V =
R = V
Ex. If R is ___________ , then I is _____________ .
As R  ____, I  ____ . This is a ___________ circuit.
R = V V =
This situation can be _______________________________ .
Body resistance can be lowered by getting __________ .

30. "It's _______________ that jolts, (shocks you)
But it's ___________ (milliamps of current) that kills."
Currents
and the
harm they
can cause:
AC tends to send heart nerves into _______________, which
can be harder to fix than simply ________________________.

31. A__________, short for 'fusible link', is a type of overcurrent protection device. Its essential component is a __________________________________________________ ____________________ Fuses usually are rated in _______________ . If the current exceeds the rating, the
metal strip melts, and it _________ the circuit. This protects the circuit from __________________ which may damage other circuit parts or ________________ .
A _______________________ is an automatically-operated electrical ______________ . Like a fuse, it is designed to protect an electrical circuit from damage caused by excess_________ Unlike a fuse, which operates once and then must be replaced, a circuit breaker ________________ once the problem that caused the excess current is fixed.

32. A downed power line
can set up a _________
through the ground.
Since the cables have
_______ R, most voltage
will be dropped along
_________________ .
If the distance between the
downed line and the source
is _________, there can be
large _________ between
2 nearby points along the
ground between your feet.
___________ or ____________!

33. IV. Series circuits - ____________________________________
___________________________________________________
circuit
element ___
wire
wire
________
potential
voltage
source
circuit
element ___
________
potential
wire
circuit
element ___
wire
Assume:
1. _____________________________________________________
2. _____________________________________________________
3. _____________________________________________________
4. _____________________________________________________

34. For a
circuit
with 2
resistors:
_______________ Conservation: V =
_______________ Conservation: I =
_______________ (Total) Resistance: Req =
__________ Law applies to the total: V =
and to each individual element: V1 =
V2 =

35. Ex. Find all the voltages and currents in the circuit below:
V1 = I1 = R1 =
V2 = I2 = R2 =
V = I = Req =

36. Form the __________ of each resistance to Req = ________ ,
and then multiply by the ___________ voltage V.
V =
20. V 40 W R1
Req
120 W R2
Req
V “divides up” ______________________________ as the R’s
This is because ___________ R requires _________ energy.
Series circuits are _______________________________.

37. Plot V vs. “distance around circuit.”
back to ____
side of the
battery
Plot V vs. “distance around circuit.”
____ side of
battery 20
V dropped across
the ______ resistor 15
potential
difference
(V)
V dropped
across the
______ R
at the ___
side of the
battery
distance around circuit
________ drop across wires because we assume ________

38. Important:
“I is ______________ everywhere in ___________ circuit” does
NOT mean that I is ___________ in _________________ circuit!
I =
I1 =
I2 =
10. V
R1=
R2 =
I =
I1 =
I2 =
I3 =
R1=
10. V
R2=
R3=
I is still the _______________ in all parts of the second
circuit, but it is a ________________ I than the first one!

39. Equivalent resistance: _________________________________
________________________________________________________
Replacing this part of the
circuit with a single
_______________ resistor:
Req = R1 + R2 = =
20. V
40 W
120 W
…gives you this circuit:
The total I =
20. V
This is the ____________ as before.

40. All _______________ circuits can be ___________________ in this way.
Req =
_____ W
V =
20 V
V =
20 V B.
Req =
_____ W
V =
12 V
V =
12 V
This can be done even if the ______________________ is not shown. C.
Req =
_____ W D.
Req =
_____ W
Req results in the _____________ as the _________________ circuit.

41. To measure I1, the current through R1, _________________
Series Circuits
__________ Hookups:
Original
circuit: R1 V R2
To measure I1, the current through R1, _________________
the circuit and ____________ an ________________ next to R1. V R1 R1 V R2 R2
Other
possibilities: R1 V V R1 R2 R2
___ is the same everywhere, so _________________________

42. To measure V1, the voltage across R1, __________disconnect
the circuit. Simply connect the ______________ across R1 V R1 R2
Original
circuit: V R1 R2
Other
possibilities: V R1 R2 V R1 R2
Similarly, to measure the _________ voltage V or V2: V R1 R2 V R1 R2

43. V. Parallel circuits - ___________________________________
___________________________________________
wire
wire
wire
________
potential
wire
circuit
element
___
circuit
element
___
circuit
element
___
circuit
element
___
voltage
source
________
potential
wire
Assume:
1. _____________________________________________________
2. _____________________________________________________
3. _____________________________________________________
4. _____________________________________________________

44. For a
circuit
with 2
resistors:
_______________ Conservation: V =
_______________ Conservation: I =
_______________ (Total) R: /Req =
__________ Law applies to the total: V =
and to each individual element: V1 =
V2 =

45. Ex. Find all the voltages and currents in the circuit below:
V1 = I1 = R1 =
V2 = I2 = R2 =
V = I = Req =

46. To find Req without using V and I:1
Req = R1 + R2 = = = =
NOTE: In a ________________ circuit,
Req is __________________ either R1 or R2.

47. Compare the _________ of the resistances R1/R2 to the
__________ of the currents: I1/I2. R1 R2 I1
But… I2
I “divides up” ______________________________ to the R’s
R1 has ______ the current b/c it has __________resistance.
Parallel circuits are _______________________________.

48. Notice what happens if one branch is __________________ :
I1= V1/R1
20. V
50 W
100 W
I2= V2/R2
20. V
50 W
100 W
These are ____________________ answers as before.
Each branch is_______________________of the others.
This is why __________________ circuits are used.

49. Plot V vs. “distance around circuit.”
back to ____
side of the
battery
Plot V vs. “distance around circuit.”
____ side of
battery 20
potential
difference
(V)
____ resistor
_____ resistor
at the ___
side of the
battery
distance around circuit
______ drop across wires because we assume _________

50. Important:
“V is ______________ everywhere in ___________ circuit” does
NOT mean that V is ___________ in ______________ circuit! V=
V1=
V2=
10. V
R1 =
R2=
V =
V1 =
V2 =
R1 =
20. V
R2=
V is the _______________ across all parts of the second
circuit, but it is a ________________ V than the first one!

51. Equivalent resistance: _________________________________
________________________________________________________
Replacing this part of the
circuit with a single
_______________ resistor:
Req = 1/(1/R1 + 1/R2) =
…gives you this circuit:
The total I =
20. V
This is the ____________ as before.

52. All _______________ circuits can be ___________________ in this way.
V =
3.0 V
V =
3.0 V
Req = ____W
This can be done even if the ______________________ is not shown. B.
Req =
_____ W C.
Req =
_____ W
Req results in the _____________ as the _________________ circuit.

53. Alternative ways to draw parallel circuits:
The circuit
at left can
also be
drawn: V R1 R2 V
or:
or: V V
NOTE: The diagram below is _________________________
because there is ________________
__________ for the current. V

54. What is the equivalent resistance between points A
Ex 1. Draw two 10-W
resistors in parallel
between points A and B.
Ex 2. Draw three 60-W
resistors in parallel
between points A and B. A A B B
What is the equivalent resistance between points A
and B in each of the examples above? (Hint: For identical
parallel resistors, divide 1 R by the ___________ of resistors.)
Ex 1: Divide _______ by ____  Req = __________
Ex 2: Divide _______ by ____  Req = __________

55. A. To measure, V1, the voltage across R1, connect the
Parallel Circuit
__________ Hookups:
Original
circuit: V R1 R2
A. To measure, V1, the voltage across R1, connect the
______________ across R1.
To measure I1, the current through R1, _________________
the circuit and _____________ an ________________ next to R1 R2 V
____ = where the ammeter could also be placed.

56. B. To measure the voltage _____________ and the current
__________ resistor R2: V R1
___ = optional
ammeter position
C. To measure the _________ voltage and current : R1 R2
___ = optional
ammeter position

57. In an ideal parallel circuit, all of the ______________
are equal, so placing the ________________ across any
element gives ___________________________ . R2 V R1
In reality, each voltage will _______________________ .
This is because the wires have a small amount of ______ ,
and so by Ohm's law: __________ , there is a small amount
of _________________ dropped along each wire.

58. VI. Electrical Power P is the _________ at which electrical
_____________________________ light, heat, mechanical, etc,
energy or vice versa.
P is a _____________ P
The units of P are watts, W ( _____________ )
1 watt = 1 W = =
Since W = , you can write:
Electrical work: W =

59. Ex. At what rate is electrical energy converted to heat
and light in a 75 W bulb?
Ex: A 55-W toaster oven is used for 25 seconds.
How much electrical energy is converted to heat?

60. Ex. A 12-W resistor carries a current of 3.0 A for 5.0 s.
a/ At what rate does the resistor convert energy?
b/ How much energy does the resistor convert in the 5.0 s?

61. Ex: How much power
is developed in the
circuit at right?
Given:
At what rate is energy converted to heat?
How much energy is converted in one minute?
Ex. What quantity does P “·” represent?

62. Ex. R1 V V R1 R2 R2
Power of resistor R1: P1 =
Power of resistor R2: P2 =
Total power: P =
or sum up the powers: P =
All of these equations work ___________________________ .

63. Ex: Find the power in each resistor and the total power.
V1 = I1 = R1 = P1 =
V2 = I2= R2 = P2 =
V = I= R = P =

64. Ex: Find the power in each resistor and the total power.
V1 = I1 = R1 = P1 =
V2 = I2= R2 = P2 =
V = I= R = P =

65. Notice both circuits above have ____________ V, R1 and R2.
Which of the two circuits would drain a battery faster?
The ____________ circuit has a ______________ Req.
This means it will have ____________ I. Because
P = ______ and both circuits have the _____ , the
_____________ circuit will develop more power.
Which resistor develops more power in the series circuit?
___ b/c both have same ___ but it has more ____________
Which develops more power in the parallel circuit?
___ b/c both have same ___ but it has more ____________

66. __________________ passed ___________ through a wire that
was submerged in __________ and found that the amount
of ________ produced was proportional to ____ and _____.
This is called_________ or _____ heating. Less ___ means
______________ electrical energy is converted to _______.
Because P = ____ , the current can be reduced if ____ is
increased. For this reason, power is transmitted at high
_____________ .
At your
house:
_________
Power
plant:
~_____
The power is
transmitted at
_____________
A substation cuts
the V to __________