Download Dear Notetaker:

BHS 120.2 – Optics II
Notetaker: Michael Christian
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Date: 01/29/2013, 2nd hour
Page1
We had recitation second hour…..
Q1
Your patient reads 1.0 M print size @ 100 cm. You enlarge the print to measure 2.5 M and
position it @ 40 cm. Find angular Magnification.
M r.s. = New size/ Old size
= 2.5/1.0 = 2.5x
M r.d. = q/q’
=100/40 = 2.5x
M ang. = (M r.d. )(M r.s).
= 6.25 X
Q2
Patient uses a +10.00 D hand-held magnifier. You tell him to hold the magnifier at 10 cm from
his eye. The angular Mag will be Less than Effective Mag.
Effective mag
M25 = Pe/4
= 10.00/4
= 2.50x
Angular Mag
M ang= kPe+1
= (0.10)(10)+1
= 1+1
= 2.00x
Q3
Patient’s BCVA= 0.3/4.0M
Target visual acuity= 1.0M
Which of the following options is most suitable for your 65 y/o patient?
+13.33 D hand-held magnifier with target print located -7.5cm from the magnifier.
Target Acuity= ¼ of BCVA
Equivalent viewing distance= 30cm/4= 7.5 cm
Equivalent viewing power= 1/0.075 m = 13.33 D
Q4
Your patient is using a +15 D hand held magnifier while holding it 5 cm from his +2 D Bifocal
ADD. The equivalent power of the magnifier-ADD combo is greater than the power of the
magnifier alone.
Pe = P1+P2-(c)(P1)(P2)
= 15+2- [(0.05)(15)(2)]
= +15.50 D
Q5
Where must the patient hold the magnifier in relation to the object so that there is no
accommodative demand?
1/Pe = 1/15.5 D = 6.45 cm
BHS 120.2 – Optics II
Notetaker: Michael Christian
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Date: 01/29/2013, 2nd hour
Page2
Q6
The objective lens of a telescope has a secondary focal length of +12 cm. The ocular lens has a
primary focal length of +4 cm. Select the INCORRECT statement:
A) The exit pupil is virtual.
B) Tube length of this TS is afocal setting is 8cm.
C) It is a Galilean TS.
D) The image formed by this TS is inverted.
M T.S.= f’ obj/ f ocular = 12/4 = 3X
This means the image is magnified and UPRIGHT. NOT inverted.
Q7
The objective lens of a given telescope has a secondary focal length of +12cm. The eye piece
has a primary focal length of -3.00cm. Select the CORRECT statement.
1) It is a Galilean TS.
2) Image formed by this TS is upright.
3) Tube length of this TS in afocal setting is 9.00cm.
4) Exit pupil is real.
Q8
Decreasing the tube length of the telescope creates Divergence in the telescope.
Q9
Increasing the tube length of the telescope adapts it for an uncorrected Hyperope.
Q10
Your patient lifts her stand magnifier (Pe = +15.00 D; column height = 3.5 cm) so that the base
of the magnifying lens is 4.5 cm off the printed material. Describe the resulting image.
1) Virtual
2) Inverted
3) Minified
4) Located between PPF and 2 PPF
Q11)
Patient’s BCVA is 0.4/2.0 M. Target acuity is 0.5 M. You prescribe a stand magnifier with +13
D lens, fixed at 3.5cm from its base. Select the statement that is INCORRECT.
1) The equivalent viewing distance is -10cm.
2) The enlargement ratio is +4.00 X
3) The virtual image is located at -6.42cm from magnifier.
4) None of the above.
Q12
A stand magnifier with an enlargement ratio of 3.00X creates an image at |10cm| from the
magnifying lens. Find the dioptric power of the magnifying lens.
M=3X
l= -10cm
L’=-10D
L=3.00/-10.00=-30 D
L’=L+P
P=+20D