Is the Image from a 12cm Focal Length Lens Virtual or Real?

AI Thread Summary
The discussion focuses on determining the nature of the image produced by a positive lens with a focal length of 12cm when an object is placed 3cm from the lens. Using the lens formula, it is calculated that the image distance is -4cm, indicating that the image is formed on the same side as the object. Since the object is within the focal length, the image is classified as virtual and erect. Participants emphasize the importance of drawing a ray diagram to visualize the situation before performing calculations. The conclusion confirms that the image is virtual and erect due to the object's proximity to the lens.
mike2007
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A positive lens has a focal length of 12cm. An object is located a distance of 3 cm from the lens.
How far is the lens from the image?
Is the image real or virtual, erect or inverted?

My attempt
f = +12cm
o = +3cm
i =?
1/o + 1/I = 1/f
1/i = 1/f – 1/o
= 1/12cm – 1/3cm
= 1/12 – 4/12
= - (3/12)
i = -4cm on the same side of the object.

Since the object lies in within the focal point, the image is virtual and erect.
 
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Always draw the ray diagram before trying to do the maths.
 
Looks good to me.
 
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