Download Pre-Lab: (Total 10 Points)

Pre-Lab: (Total 10 Points)
Hopefully here for the Pre-Lab
Name(Print then sign): ___________________________________________________
Lab Day: ___________________Section: ________TA__________________________
This assignment must be completed individually and turned in to your TA at the
beginning of lab. You will not be allowed to begin the lab until you have
completed this assignment
1.
Fill in the blanks:
Fuel cells are used for direction conversion of the energy of combustion reactions to ______________. A
fuel cell is a ______________ in which electricity is generated by a combustion reaction. A fuel cell
provides a ______________ voltage that can be used to power motors, lights or any number of electrical
appliances.
2.
T or F
At the anode, oxidation of the fuel takes place.
3.
T or F
The fuel cell emissions will be nothing but water vapor.
4.
T or F
The efficiency of fuel cells, chemical-to-electric energy conversion, is approximately 40%.
Review of series and parallel circuits:
In a series circuit, the electrons in the current have to pass through all the components, which are arranged
in a line. Consider a typical series circuit in which there are three resistors of value R 1 , R 2 , and R 3 .
There are two key
points about a series
circuit:


Therefore:
VT  V1  V2  V3
The current
throughout
the circuit is
the same.
The voltages
add up to the
battery
voltage.
From Ohm’s Law:

VT  IR T ;


V1  IR 1 ;
V2  IR 2 ;

V3  IR 3 ;
 IR T  IR 1  IR 2  IR 3
Therefore:
R Tot  R 1  R 2  R 3
5.
In the circuit below, the current is 100 mA.
(a) What is the current
in each resistor?
(b) What is the voltage
across each resistor?
(c) What is the total
resistance?
(d) What is the battery
voltage?
Parallel circuits have
their components in
parallel branches so that an individual electron can go through one of the branches but not the others. The
current splits into the available number of branches.
In this
case, the
current
will split
into three.
For a
parallel
circuit:


ge across each branch is the same.
The currents in each branch add up to the total current.
From this:
T
h
e
v
ol
ta
I Tot  I 1  I 2  I 3
From Ohm’s Law:
6.
I T  V; I1  V; I 2  V; I 3  V
RT
R1
R2
R3
V  V V V
R T R1 R 2 R 3
 1/R Tot  1/R 1  1/R 2  1/R 3
This question refers to the circuit below.
(a) What is
the total
resistance
of the
circuit?
(b) What is
the current
through
each
resistor?
(c) What is
the total current?
For resistors in both series and parallel, follow these
guidelines:


7.
circuit?
Work out the total resistance of the parallel
combination.
Work out the total resistance of the circuit by
adding your answer in the previous step to the
values of the series resistors.
What is the single resistor equivalent of this