Physics A convex lens of focal length 20 cm is placed at a distance 10 cm from a glass plate (refractive index=3/2) of thickness 3 cm. An object is placed at a distance 40 cm from lens on the other side of glass plate, the image of this object will formed at a distance of- 19 cm from glass plate 30 cm from glass plate. 31 cm from glass plate. 28 cm from glass plate?

Question

Answer

Answer:

The problem is related to the formation of an image by a convex lens and a glass plate. The given data can be summarized as:

Focal length of the convex lens (f) = 20 cm

Distance of the lens from the glass plate (u) = 10 cm

Thickness of the glass plate (t) = 3 cm

Refractive index of the glass plate (n) = 3/2

Distance of the object from the lens (v) = 40 cm

Step 1: Finding the position of the image formed by the convex lens

The first step is to find the position of the image formed by the convex lens. We can use the lens formula to find the position of the image:

1/f = 1/v - 1/u

Substituting the given values, we get:

1/20 = 1/v - 1/10

Solving for v, we get:

v = 40 cm

Therefore, the image formed by the convex lens is at a distance of 40 cm from the lens.

Step 2: Finding the position of the final image formed by the glass plate

The image formed by the convex lens is at a distance of 40 cm from the lens. This image acts as the object for the glass plate. The glass plate is of thickness 3 cm and has a refractive index of 3/2. Therefore, the image will be displaced by a distance:

d = t(n-1)

Substituting the given values, we get:

d = 3(3/2-1) = -3/2 cm

The negative sign indicates that the image is displaced in the opposite direction to the light. Therefore, the image will be at a distance of:

v' = v - d = 40 - (-3/2) = 41.5 cm

Therefore, the final image is formed at a distance of 41.5 cm from the convex lens.

Step 3: Finding the position of the final image with respect to the glass plate

The final image is formed at a distance of 41.5 cm from the convex lens. We need to find its position with respect to the glass plate. To do this, we need to find the distance between the lens and the glass plate:

u' = u + f = 10 + 20 = 30 cm

Now, using the formula:

1/f' = 1/v' - 1/u'

Substituting the values, we get:

1/f' = 1/41.5 - 1/30

Solving for f', we get:

f' = 126 cm

Therefore, the final image is formed at a

Answer

Answer is 31cm from glass plate

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