In what condition, the image formed by concave mirror is virtual?

In what condition, the image formed by concave mirror is virtual?

Ans: –When object is between focal point and pole of the mirror then the image will be formed in the concave mirrors.

 

At what position will the reflected ray shown in Fig. 15.17 intersect the principal axis beyond focus or before focus?

Ans: – From the image it is clear that the reflected rays intersect the principal axis before focus.

 

What type of image will be formed if an object is placed beyond centre of curvature infront of a concave mirror?

Ans: –  When an object is placed beyond the centre of curvature infront of a concave mirror then the image will be real, inverted and small in size.

 

Find the position of the object placed infront of a concave mirror of focal length20 cm if image is formed at the distance of 30 cm from the mirror.

Ans: –We know, 1/f = 1/v + 1/u;

Here, f=20cm, v=30cm,

So, 1/20 = 1/30 + 1/u,

Or, u= 60cm.

 

Write two uses of concave mirror.

Ans: – The uses of concave mirror –

• • In car headlights.
  • In solar cooker.

 

Write the nature of image formed in convex mirror.

Ans: –  Image will be smallest and virtual in convex mirror.

 

Find the position of the image formed in convex mirror of focal length 12 cm when object is placed at the distance of (i) 8 cm, (ii) 12 cm and (iii) 18 cm from the mirror.

Ans: – As we know, 1/f = 1/v + 1/u,

In case 1, f=12cm, u=-8cm,

So, 1/12 = 1/v – 1/8;

Or, v= 4.8cm.

In case 2, f=12cm, u=-12cm.

So, 1/12= 1/v + 1/(-12) ;

Or, v= 6cm.

In case 3, f=12cm, u=-18cm,

So, 1/12 = 1/v – 1/18;

Or, v= 7.2cm.

 

Complete the following table with corresponding positions of object and image in case of concave mirror.

Ans: –

Position of object	Position of image
(i)                  At F	At infinity
(ii)                Between F and 2F	Beyond 2F
(iii)               Beyond 2F	Between F and 2F.
(iv)              Between F and 2F	Beyond 2F.
(v)                Beyond 2F	Between F and 2F.

 

Write two uses of convex mirror.

Ans: – This convex mirror is used in rare view mirror and in car looking glass.

 

Does concave mirror always converges the light rays?

Ans: – No the concave mirror doesn’t converge the light rays.

 

Write the conditions to produce a magnified image in concave mirror.

Ans: – For produce a magnified image in concave mirror the mirror should be placed between F and 2F.

 

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