Question

An electrical pole and a screen are placed on a flat suface at a distance of 50cm in what position of convex lens of focal length 7cm will the image of lamp be sharp. Plz answer fast!​

Answer 1

Answer:

The following steps are to be taken to solve the query:

1) Using the distances in the diagram above we get u = - x and v = d - x.

2) Now, apply the lens formula and find the relation between the distances.

You will get a quadratic relation between x,

f and d as x

2

- xd + fd = 0 -------(1)

3) Substitute the value of d = 100 cm

and f = 21 cm to find the value of x.

so when we put f=21 and d=100

finally

Substituting these values in equation 1,

we get x

1

=70cm and x

2

=30cm

solution