Lenses - GRE Subject Test: Physics
Card 1 of 12
The focal length of a thin convex lens is 
. A candle is placed 
to the left of the lens. Approximately where is the image of the candle?
The focal length of a thin convex lens is
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Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between 
on the right side of the lens.
Alternatively, one can apply the thin lens equation:
Where 
is the object distance 
and 
is the focal length 
. Plug in these values and solve.
Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between
Alternatively, one can apply the thin lens equation:
Where
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A candle 
tall is placed 
to the left of a thin convex lens with focal length 
. What is the height and orientation of the image created?
A candle
Tap to reveal answer
First, find the image distance 
from the thin lens equation:
Magnification of a lens is given by:
Where 
and 
are the image height and object height, respectively. The given object height is 
, which we can use to solve for the image height:
Because the sign is negative, the image is inverted.
First, find the image distance
Magnification of a lens is given by:
Where
Because the sign is negative, the image is inverted.
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Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at 
?
Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at
Tap to reveal answer
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians, 
is the wavelength of light, and 
is the diameter the lens in question. Solving for 
and converting 3 arcseconds into radians, one can approximate the diameter to be about 
:
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians,
← Didn't Know|Knew It →
The focal length of a thin convex lens is . A candle is placed to the left of the lens. Approximately where is the image of the candle?
The focal length of a thin convex lens is
Tap to reveal answer
Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between on the right side of the lens.
Alternatively, one can apply the thin lens equation:
Where is the object distance and is the focal length . Plug in these values and solve.
Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between
Alternatively, one can apply the thin lens equation:
Where
← Didn't Know|Knew It →
A candle tall is placed to the left of a thin convex lens with focal length . What is the height and orientation of the image created?
A candle
Tap to reveal answer
First, find the image distance from the thin lens equation:
Magnification of a lens is given by:
Where and are the image height and object height, respectively. The given object height is , which we can use to solve for the image height:
Because the sign is negative, the image is inverted.
First, find the image distance
Magnification of a lens is given by:
Where
Because the sign is negative, the image is inverted.
← Didn't Know|Knew It →
Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at ?
Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at
Tap to reveal answer
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians, is the wavelength of light, and is the diameter the lens in question. Solving for and converting 3 arcseconds into radians, one can approximate the diameter to be about :
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians,
← Didn't Know|Knew It →
The focal length of a thin convex lens is . A candle is placed to the left of the lens. Approximately where is the image of the candle?
The focal length of a thin convex lens is
Tap to reveal answer
Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between on the right side of the lens.
Alternatively, one can apply the thin lens equation:
Where is the object distance and is the focal length . Plug in these values and solve.
Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between
Alternatively, one can apply the thin lens equation:
Where
← Didn't Know|Knew It →
A candle tall is placed to the left of a thin convex lens with focal length . What is the height and orientation of the image created?
A candle
Tap to reveal answer
First, find the image distance from the thin lens equation:
Magnification of a lens is given by:
Where and are the image height and object height, respectively. The given object height is , which we can use to solve for the image height:
Because the sign is negative, the image is inverted.
First, find the image distance
Magnification of a lens is given by:
Where
Because the sign is negative, the image is inverted.
← Didn't Know|Knew It →
Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at ?
Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at
Tap to reveal answer
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians, is the wavelength of light, and is the diameter the lens in question. Solving for and converting 3 arcseconds into radians, one can approximate the diameter to be about :
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians,
← Didn't Know|Knew It →
The focal length of a thin convex lens is . A candle is placed to the left of the lens. Approximately where is the image of the candle?
The focal length of a thin convex lens is
Tap to reveal answer
Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between on the right side of the lens.
Alternatively, one can apply the thin lens equation:
Where is the object distance and is the focal length . Plug in these values and solve.
Because the object is beyond 2 focal lengths of the lens, the image must be between 1 and 2 focal lengths on the opposite side. Therefore, the image must be between
Alternatively, one can apply the thin lens equation:
Where
← Didn't Know|Knew It →
A candle tall is placed to the left of a thin convex lens with focal length . What is the height and orientation of the image created?
A candle
Tap to reveal answer
First, find the image distance from the thin lens equation:
Magnification of a lens is given by:
Where and are the image height and object height, respectively. The given object height is , which we can use to solve for the image height:
Because the sign is negative, the image is inverted.
First, find the image distance
Magnification of a lens is given by:
Where
Because the sign is negative, the image is inverted.
← Didn't Know|Knew It →
Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at ?
Sirius is a binary star system, consisting of two white dwarfs with an angular separation of 3 arcseconds. What is the approximate minimum diameter lens needed to resolve the two stars in Sirius for an observation at
Tap to reveal answer
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians, is the wavelength of light, and is the diameter the lens in question. Solving for and converting 3 arcseconds into radians, one can approximate the diameter to be about :
The Rayleigh Criterion gives the diffraction limit on resolution of a particular lens at a particular wavelength:
Where theta is the angular resolution in radians,
← Didn't Know|Knew It →