Question

a concave lens of focal length 30cm. Find the position and magnification of the image for an object placed in front of it at a distance 30cm.state whether the object is real or virtual

Answer 1

Answer:

The image is real and diminished.

Explanation:

Let's write down the lens formula below.

1/f = 1/u + 1/v

Where:

f = focal length

u = Object distance

v = Image distance

In our case we have:

f = 30 cm

v = 30 cm

1/30 = 1/u + 1/30

1/u = 1/30 - 1/30

1/u = 1/0

Object is placed at infinity.

The characteristics of the image formed is therefore:

• real
• inverted
• highly diminished

Answer 2

Answer:

Explanation:

Given :-

Focal length = 30 cm

Image distance = 30 cm

Solution :-

By the lens formula,

⇒ 1/f = 1/u + 1/v

⇒ 1/30 = 1/u + 1/30

⇒ 1/u = 1/30 - 1/30

⇒ 1/u = 1/0

⇒ u = 0 cm

Now, nature of image,

Object is placed at infinity.

The characteristics of the image formed is therefore:

• Real
• Inverted
• Highly diminished