PHYS 1402 FINAL WTC EXAM
QUESTIONS WITH CORRECT ANSWERS
A |fish |appears |to |be |6.00 |m |below |the |surface |of |a |pond |when |viewed |almost |directly |above |by |a
|fisherman. |What |is |the |actual |depth |of |the |fish? |(n |water |= |1.33) |- |VERIFIED |ANSWER✔✔-(6.00)(1.33)
|= |7.98
A |thin |double |convex |lens |is |to |focus |the |image |of |an |object |onto |a |screen |so |that |the |image |is |life-
sized. |The |lens |has |equal |radii |of |95 |cm |and |the |refractive |index |is |n |= |1.4. |(a) |What |is |the |distance |d
|from |image |to |screen? |(b) |What |is |the |total |distance |L |between |object |and |image? |- |VERIFIED
|ANSWER✔✔-(1.4-1)(1/95)(2) |= |0.00842105
1/0.00842105 |= |118.75(2) |= |238
A |double |convex |thin |glass |lens |has |equal |radii |of |curvature. |The |focal |length |of |the |lens |is |+26.3 |cm
|and |the |index |of |refraction |of |the |glass |is |1.52. |The |radius |of |curvature |of |each |convex |surface, |in
|cm, |is |closest |to: |- |VERIFIED |ANSWER✔✔-1/26.3 |= |0.52(2/R)
R |= |27
The |radius |of |curvature |of |the |curved |side |of |a |plano-convex |lens |made |of |glass |(n |= |1.64) |is |40 |cm.
|What |is |the |focal |length |of |the |lens? |- |VERIFIED |ANSWER✔✔-1/f |= |(0.64)(1/40)
1/f |= |0.016
1/0.016 |= |62.5
A |thin |hemispherical |bowl |of |clear |plastic |floats |on |water |in |a |tank. |The |radius |of |the |bowl |is |50 |cm
|and |the |depth |of |the |bowl |in |water |is |10 |cm. |The |depth |of |the |water |(n |= |1.33) |in |the |tank |is |h |=
|200 |cm. |An |object |8.0 |cm |long |is |on |the |bottom |of |the |tank |directly |below |the |bowl. |The |object |is
|viewed |from |directly |above |the |bowl. |Ignore |the |refractive |effects |of |the |plastic. |In |the |figure, |the
|character |of |the |image |is: |- |VERIFIED |ANSWER✔✔-virtual |and |errect
A |simple |camera |lens |with |focal |object |length |fo |= |5 |cm |perfectly |focuses |the |image |of |an |object |on |a
|photographic |film |located |a |distance |10 |cm |away |from |the |lens. |The |object |now |moves |away |from
|the |lens |and |the |new |focal |distance |is |9 |cm. |(a) |How |far |did |the |object |move? |(b) |What |is |the |new
|magnification? |- |VERIFIED |ANSWER✔✔-(5)(10)/(10-5) |= |10
, (5)(9)/(9-5) |= |11.25
11.25-10 |= |1.25
9/11.25 |= |0.8
A |lens |of |focal |length |60 |mm |is |used |as |a |magnifier. |The |object |being |viewed |is |6.4 |mm |long, |and |is
|positioned |at |the |focal |point |of |the |lens. |The |angle |subtended |by |the |image |at |infinity, |in
|milliradians, |is |closest |to: |- |VERIFIED |ANSWER✔✔-25/6 |= |4.16
.64/25 |= |0.0256
(0.0256)(4.16) |= |107
A |myopic |girl |wears |eyeglasses |that |allow |her |to |have |clear |distant |vision. |The |power |of |the |lenses |of
|her |eyeglasses |is |-1 |diopters. |Without |eyeglasses, |the |far |point |of |the |girl |is |closest |to: |- |VERIFIED
|ANSWER✔✔-1/-1 |= |1.0 |m
In |a |35 |mm |single |lens |reflex |camera |(SLR) |the |distance |from |the |lens |to |the |film |is |varied |in |order |to
|focus |on |objects |at |varying |distances. |Over |what |range |must |a |lens |of |70 |mm |focal |length |vary |if |the
|camera |is |to |be |able |to |focus |on |objects |ranging |in |distance |from |infinity |down |to |1.3 |m |from |the
|camera? |- |VERIFIED |ANSWER✔✔-1/70 |= |1/1300 |+ |1/q
q |= |73.98
73.98 |- |70 |= |3.98
An |astronomical |telescope |is |made |from |two |lenses: |the |objective |lens |has |a |focal |length |of |f |= |130
|cm, |and |the |eyepiece |lens |has |a |focal |length |of |f |= |23 |cm. |(a) |What |is |the |total |length |of |the
|telescope? |(b) |What |is |the |angular |magnification |of |the |telescope? |(c) |What |is |the |magnification |if
|the |telescope |is |viewed |by |looking |through |the |objective |lens |first? |- |VERIFIED |ANSWER✔✔-130 |+ |23
|= |153
130/23 |= |5.65
23/130 |= |0.18
An |optical |engineer |needs |to |ensure |that |the |bright |fringes |from |a |double-slit |are |15.7 |mm |apart |on
|a |detector |that |is |1.81 |m |from |the |slits. |If |the |slits |are |illuminated |with |633 |nm |light, |how |far |apart
|should |the |slits |be? |- |VERIFIED |ANSWER✔✔-15.7x10-3 |/ |1.81 |= |0.00867
tan-1(0.00867) |= |0.49697
QUESTIONS WITH CORRECT ANSWERS
A |fish |appears |to |be |6.00 |m |below |the |surface |of |a |pond |when |viewed |almost |directly |above |by |a
|fisherman. |What |is |the |actual |depth |of |the |fish? |(n |water |= |1.33) |- |VERIFIED |ANSWER✔✔-(6.00)(1.33)
|= |7.98
A |thin |double |convex |lens |is |to |focus |the |image |of |an |object |onto |a |screen |so |that |the |image |is |life-
sized. |The |lens |has |equal |radii |of |95 |cm |and |the |refractive |index |is |n |= |1.4. |(a) |What |is |the |distance |d
|from |image |to |screen? |(b) |What |is |the |total |distance |L |between |object |and |image? |- |VERIFIED
|ANSWER✔✔-(1.4-1)(1/95)(2) |= |0.00842105
1/0.00842105 |= |118.75(2) |= |238
A |double |convex |thin |glass |lens |has |equal |radii |of |curvature. |The |focal |length |of |the |lens |is |+26.3 |cm
|and |the |index |of |refraction |of |the |glass |is |1.52. |The |radius |of |curvature |of |each |convex |surface, |in
|cm, |is |closest |to: |- |VERIFIED |ANSWER✔✔-1/26.3 |= |0.52(2/R)
R |= |27
The |radius |of |curvature |of |the |curved |side |of |a |plano-convex |lens |made |of |glass |(n |= |1.64) |is |40 |cm.
|What |is |the |focal |length |of |the |lens? |- |VERIFIED |ANSWER✔✔-1/f |= |(0.64)(1/40)
1/f |= |0.016
1/0.016 |= |62.5
A |thin |hemispherical |bowl |of |clear |plastic |floats |on |water |in |a |tank. |The |radius |of |the |bowl |is |50 |cm
|and |the |depth |of |the |bowl |in |water |is |10 |cm. |The |depth |of |the |water |(n |= |1.33) |in |the |tank |is |h |=
|200 |cm. |An |object |8.0 |cm |long |is |on |the |bottom |of |the |tank |directly |below |the |bowl. |The |object |is
|viewed |from |directly |above |the |bowl. |Ignore |the |refractive |effects |of |the |plastic. |In |the |figure, |the
|character |of |the |image |is: |- |VERIFIED |ANSWER✔✔-virtual |and |errect
A |simple |camera |lens |with |focal |object |length |fo |= |5 |cm |perfectly |focuses |the |image |of |an |object |on |a
|photographic |film |located |a |distance |10 |cm |away |from |the |lens. |The |object |now |moves |away |from
|the |lens |and |the |new |focal |distance |is |9 |cm. |(a) |How |far |did |the |object |move? |(b) |What |is |the |new
|magnification? |- |VERIFIED |ANSWER✔✔-(5)(10)/(10-5) |= |10
, (5)(9)/(9-5) |= |11.25
11.25-10 |= |1.25
9/11.25 |= |0.8
A |lens |of |focal |length |60 |mm |is |used |as |a |magnifier. |The |object |being |viewed |is |6.4 |mm |long, |and |is
|positioned |at |the |focal |point |of |the |lens. |The |angle |subtended |by |the |image |at |infinity, |in
|milliradians, |is |closest |to: |- |VERIFIED |ANSWER✔✔-25/6 |= |4.16
.64/25 |= |0.0256
(0.0256)(4.16) |= |107
A |myopic |girl |wears |eyeglasses |that |allow |her |to |have |clear |distant |vision. |The |power |of |the |lenses |of
|her |eyeglasses |is |-1 |diopters. |Without |eyeglasses, |the |far |point |of |the |girl |is |closest |to: |- |VERIFIED
|ANSWER✔✔-1/-1 |= |1.0 |m
In |a |35 |mm |single |lens |reflex |camera |(SLR) |the |distance |from |the |lens |to |the |film |is |varied |in |order |to
|focus |on |objects |at |varying |distances. |Over |what |range |must |a |lens |of |70 |mm |focal |length |vary |if |the
|camera |is |to |be |able |to |focus |on |objects |ranging |in |distance |from |infinity |down |to |1.3 |m |from |the
|camera? |- |VERIFIED |ANSWER✔✔-1/70 |= |1/1300 |+ |1/q
q |= |73.98
73.98 |- |70 |= |3.98
An |astronomical |telescope |is |made |from |two |lenses: |the |objective |lens |has |a |focal |length |of |f |= |130
|cm, |and |the |eyepiece |lens |has |a |focal |length |of |f |= |23 |cm. |(a) |What |is |the |total |length |of |the
|telescope? |(b) |What |is |the |angular |magnification |of |the |telescope? |(c) |What |is |the |magnification |if
|the |telescope |is |viewed |by |looking |through |the |objective |lens |first? |- |VERIFIED |ANSWER✔✔-130 |+ |23
|= |153
130/23 |= |5.65
23/130 |= |0.18
An |optical |engineer |needs |to |ensure |that |the |bright |fringes |from |a |double-slit |are |15.7 |mm |apart |on
|a |detector |that |is |1.81 |m |from |the |slits. |If |the |slits |are |illuminated |with |633 |nm |light, |how |far |apart
|should |the |slits |be? |- |VERIFIED |ANSWER✔✔-15.7x10-3 |/ |1.81 |= |0.00867
tan-1(0.00867) |= |0.49697
