Exam 1 Concepts

Exam 1 Concepts - Concept Test #1 If the “bulls eye”...

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Unformatted text preview: Concept Test #1 If the “bulls eye” represents the true value, which of the following is precise but not accurate? A. Neither B. Accurate? Consider the average. C. Precise D. Accurate & Precise Concept Test #2 Express the following product to the correct number of significant figures. (0.0340 yd) x (27.08 yd) x (3 ft/yd)2 (The calculator gives 8.28648) A. 8 B.  8.3 C.  8.29 C. 8.29 D.  8.286 E.  8.2865 0.0340 yd = 3 sf 27.08 yd = 4 sf 3 ft/yd = ∞ sf ∴ answer = 3 sf Concept Test #3 Express the following sum to the correct number of significant figures. 997.4 + 6.0321 (The calculator gives 1003.4321) A. 1003 B.  1003.4 B. 1003.4 C.  1003.43 D.  1003.432 E.  1003.4321 997.4 = 1 decimal place 6.0321 = 4 decimal places ∴ answer = 1 decimal place Concept
Test
#4
 Suppose
 we
 try
 to
 determine
 the
 length
 l
 of
 an
 oil
 plume
 by
 measuring
three
other
lengths,
l1,
l2,
and
l3
for
which
l
=
l1l2/l3.

 Suppose
l1
=
200
±
2
D.,
l2
=
5.5
±
0.1
D.,
and
l3
=10.0
±
0.4
D.

 The
uncertainty
in
l
is:
 (A) 
1.5
D
 
5
D
 (B) 
5
D
 (C) 
18
D
 Hint:
Error
propagaNon
is
the
same
for
mulNplicaNon
and
division:
 (%e12
+
%e22
+
……)1/2
 Confidence
Intervals
 (The
true
mean
and
measured
mean
are
different
because
we
 can
never
do
enough
trials
to
find
the
true
mean.)
 Concept
Test
#6
 I
 ask
 200
 randomly
 selected
 CU
 students
 how
 much
 money
 they
 donated
 to
 charity
 over
 the
 past
 week.
 The
 sample
 mean
 for
 the
 200
 students
 is
 $42.35.
 Therefore,
I
can
make
the
following
claim:

 CU students donated an average of $42.35 to chari9es last week.
 (A)
True 
 
(B)
False

 Using
Confidence
Intervals
 Concept
Test
#
7
 The
two
oil
plumes
have
the
same
hydrocarbon
 concentraNon.
 (A) 
True
 (B) 
False
 Sources
of
Noise
in
Instrumental
Analysis
 Concept
Test
 The
rise
Nme
of
a
measurement
with
a
bandwidth
of
0.033
kHz
is:
 (A) 
10
sec
 (B) 
1
sec
 (C) 
10
msec
 
 10
msec Sources
of
Noise
in
Instrumental
Analysis
 Concept
Test
 A
 faster
 measurement
 with
 lower
 RMS
 noise
 may
 be
 made
 by
 decreasing
the
bandwidth:
 (A) 
True
 (B) 
False
 False
 Decreasing
the
bandwidth
decreases
the
noise
but
slows
the
 rise
Nme.
 Sources
of
Noise
in
Instrumental
Analysis
 Concept
Test
 You
 are
 performing
 a
 measurement
 with
 an
 instrument
 that
 collects
a
data
point
every
1
sec.
You
find
that
this
response
Nme
 is
too
slow
so
you
change
the
sebngs
to
collect
data
every
1
 µs.
 The
noise
of
the
measurement
will:
 Increase
by
1000‐fold
 (A)
Increase
by
1000‐fold
 (B)
Decrease
by
106‐fold
 (C)
Decrease
by
1000‐fold
 Sources
of
Noise
in
Instrumental
Analysis
 Concept
Test
 You
 are
 performing
 a
 measurement
 with
 an
 instrument
 that
 collects
a
data
point
every
1
sec.
You
find
that
this
response
Nme
 (aka,
 rise
 Nme)
 is
 too
 slow
 so
 you
 change
 the
 sebngs
 to
 collect
 data
every
1
µs.
The
noise
of
the
measurement
will:
 IniNally,
data
points
were
collected
with
a
frequency
bandwidth
 of
1
Hz
(1
pt/sec).
The
bandwidth
was
then
changed
to
1
 x
106
 pts/sec.
(106)1/2
=
1000.
 Sources
of
Noise
in
Instrumental
Analysis
 Concept
Test
 Many
detecNon
systems
are
cooled
with
liquid
nitrogen.
Cooling
a
 detector
will:
 (A) 
Increase
the
rise
Nme
 (B) 
Decrease
the
rise
Nme
 (C) 
Decrease
the
noise
 ν
=
(4kTRΔf)1/2
 ProperNes
of
ElectromagneNc
RadiaNon
 Concept
Test
 Which
 of
 the
 following
 changes
 when
 light
 passes
 from
 one
 medium
to
another?
 (A) 
Frequency
 (B) 
Wavelength
 (C) 
Speed
 
(D)
B
and
C
 (D) 
B
and
C
 ReflecNon
of
RadiaNon
 ReflecNon
also
always
occurs
at
interfaces.
 Ir
 Io
 =

 (n2
–
n1)2
 (n2
+
n1)2
 Concept
Test
 To
minimize
reflected
losses,
one
should
try
to:
 (A) 
Maximize
the
difference
between
n1
and
n2
 (B)  
Match
n1
and
n2
 (B)
Match
n 1
and
n2
 (C)  
Use
materials
with
small
n
values
 See
Example
6‐2
for
a
quanNtaNve
calculaNon.
 Molecular
PotenNal
Energy
 Concept
Test
 What
happens
if
we
irradiate
the
molecules
with
light
equal
in
 energy
 to
 the
 difference
 between
 the
 n
 =
 0
 and
 1
 vibraNonal
 levels?
 (A)  
The
electron
will
move
from
the
ground
state
orbital
to
an
excited
state
orbital.
 (B)
The
molecule
will
vibrate
with
a
difference
frequency
but
the
electron
will
remain
 (B)  
 
 The
 molecule
 will
 vibrate
 with
 a
 difference
 frequency
 but
 the
 electron
 will
 in
the
same
orbital.
 remain
in
the
same
orbital.
 (C)  
A
and
B
will
happen.


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This note was uploaded on 02/23/2011 for the course CHEM 4181 at Colorado.

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