Question

Q25. In the below set-up, the focal length of the concave mirror is 4.0 cm. Where should the screen be

placed on the scale to obtain a sharp image​

Answer 1

Answer:

The screen should be placed at a distance of 54 cm on the object side of the mirror to obtain a sharp image. The image is real, inverted and enlarged in size. A concave lens of focal length 15 cm forms an image 10 cm from the lens.

Answer 2

Answer:

The screen be placed on focus = 4cm the scale to obtain a sharp image​

Step-by-step explanation:

It is known to us that $\frac{1}{u} +\frac{1}{v} =\frac1f$ where u = object distance, v = image distance and for = focal length.

So here focal length of the mirror is given and we know that if we need to form a sharp image the object must be at infinity.

So u = $\infty$ and now putting these values in above equation we get
$\frac{1}{\infty} +\frac1v=\frac1f$

From here we can see that image is formed at focus so V=4cm.
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