Size of Mirror

Q. For a plane mirror, if an object moves with a velocity 'v' towards the mirror, then the image moves with a velocity 2v. How?

Q. A man is $180\text{cm}$ tall and his eyes are $10\text{cm}$ below the top of his head. In order to see this entire height right from toe to head, he uses a plane mirror kept at a distance of $1\text{m}$ from him. The minimum length of the plane mirror is

1. $90\text{cm}$
2. $85\text{cm}$
3. $170\text{cm}$
4. $180\text{cm}$

Q. In displacement method, the distance between object and screen is 96cm. The ratio of length of two images formed by a convex lens placed between them is 4.84.

1. Ratio of the length of object to the length of shorter image is $\frac{11}{5}$
2. Distance between the two positions of the lens is 36cm.
3. Focal length of the lens is 22.5cm.
4. Distance of the lens from the shorter image is 30cm.

Q. A person $1.6\text{m}$ tall is standing at the centre between two walls $3\text{m}$ high. What is the minimum size of a plane mirror fixed on the wall in front of him, if the person wants to see the image of the full height of the wall behind him?

1. $0.8\text{m}$
2. $1\text{m}$
3. $2.3\text{m}$
4. $1.5\text{m}$

Q. A person is standing in front of a plane mirror.If the mirror recedes with velocity v , the relative speed of person and his image per second is-
1)0
2)v
3)2v
4)v/2

Q. Why the minimum height of a plane mirror to see once full size image is equal to half the height of the person.how to prove this?

Q. What should be the minimum height of the mirror so that a person can see the full wall of height h behind him? (Assume the man to be at the centre of the wall and the mirror.)

1. $h$
2. $\frac{h}{2}$
3. $\frac{h}{3}$
4. $\frac{h}{4}$

Q.

If the mirror moves away from the object with speed $v$ units, then find the speed of the image that moves away from the object.

Q. When a mirror is rotated through an angle $\theta$. The reflected ray from it turns through an angle of

1. $\theta$
2. $\frac{\theta }{2}$
3. $2\theta$
4. $0$

Q. A point object $O$ is placed in front of a plane mirror as shown in the figure. In order to see the image in mirror, the region where a person must place his eyes is best represented as:

1. 
2. 
3. 
4. 

Q. A child is standing in front of a straight plane mirror. His father is standing behind him, as shown in the fig. The height of the father is double the height of the child. What is the minimum length of the mirror required so that the child can completely see his own image and his fathers image in the mirror? Given that the height of father is $2H$.

1. $H/2$
2. $5H/6$
3. $Noneofthese$
4. $3H/2$

Q. If the separation between the two eyes of a man is d, what should be the minimum width of the mirror in which the man could see the full image of his face of width w, using both of his eyes.

1. $\frac{1}{2}(w+d)$
2. $(w-d)$
3. $\frac{1}{2}(w-d)$
4. $\frac{1}{2}w$

Q.

Two prisms of identical geometrical shape are combined with their refracting angles oppositely directed. The materials of the prisms have refractive indices 1.52 and 1.62 for violet light. A violet ray is deviated by ${1.0}^{\circ }$ when passes symmetrically through this combination. What is the angle of the prisms ?

Q.

Which of the following is not a feature of a plane mirror image?

1. The size of the image is bigger than the object.

2. The final image obtained is erect.

3. The image has a lateral inversion.

4. The image obtained is virtual.

Q. Two plane mirrors $M_1$ and $M_2$ are inclined at ${30}^{\circ }$to the vertical. A point object $\left(\text{O}\right)$ is placed symmetrically between them at a distance of $4\text{cm}$ from each mirror. Find the distance of the object from the second image formed in mirror $M_1$.

1. $8\text{cm}$
2. $4\sqrt{3}\text{cm}$
3. $8\sqrt{3}\text{cm}$
4. $8\sqrt{2}\text{cm}$

Q. An object is at a distance of $20\text{m}$ from a convex lens of focal length $0.3\text{m}$. The lens forms an image of the object. If the object moves away from the lens at a speed of $5\text{m/s}$, the speed & direction of the image will be:

1. $0.92\times {10}^3\text{m/s},$ away from lens
2. $2.26\times {10}^{-3}\text{m/s},$ away from lens
3. $1.16\times {10}^{-3}\text{m/s},$ towards the lens
4. $3.22\times {10}^{-3}\text{m/s},$ towards the lens

Q. In the displacement method, the sizes of image in the two positions of the lens between the object and the screen are $9\text{cm and}4\text{cm}$ respectively. The size of the object must be:

Q. Calculate the minimum size of a plane mirror fixed on the wall of a room in which an observer at the centre of the room can see the full image of the wall behind him.

Q. A tall man of height $6$ feet wants to see his full image. Then the minimum required length of the mirror will be

1. $12$ feet
2. $3$ feet
3. $6$ feet
4. Any length

Q. A man of height $180$ cm is standing in front of a plane mirror. His eyes are at a height of $170$cm from the floor. Find the minimum height of the mirror?

Q. A person of height h standing at the centre of room looking towards a plane mirror hanging on a wall, can see the bottom edge of the wall behind him if minimum length of the mirror is:

1. $h$
2. $h/2$
3. $h/3$
4. $h/4$

Q. A person is in a room whose ceiling and two adjacent walls are mirrors. How many images are formed :

1. $5$
2. $6$
3. $7$
4. $8$

Q. There are two plane mirrors with reflecting surface facing each other. Both the mirrors are moving with speed $v$ away from each other. A point object is placed between the mirrors. The velocity of the image formed due to $n-th$ reflection will be :

1. $2nv$
2. $nv$
3. $3nv$
4. $4nv$

Q. A man stands in a room with his eyes at the center of the room. The height of the ceiling is $H$. The length of the shortest plane mirror, fixed on the wall in front of the man, so that the man can see the full image of the wall behind him is:

1. $\frac{H}{2}$
2. $\frac{H}{3}$
3. $\frac{2H}{3}$
4. $\frac{H}{4}$

Q. What should be the minimum height of a plane mirror so that a $6$ft tall man can see his full view image standing in front of the mirror?

1. $6$ $ft$
2. $12$ $ft$
3. $2$ $ft$
4. $3$ $ft$

Q. A flat mirror $M$ is arranged parallel to a wall $W$ at a distance $L$ from it as shown in the figure. The light produced by a point source $S$ kept on the wall is reflected by the mirror and produces a light patch on the wall. If the mirror moves with velocity $v$ towards the wall.

1. The patch of light will not move on the wall.
2. The width of the light patch on the wall remains the same.
3. As the mirror comes closer the patch of light will become larger and shift away from the wall with speed larger than $v$.
4. The patch of light will move with the speed $v$ on the wall.

Q. A man of height 170 cm wants to see his complete image in the mirror (while standing) His eyes is at a height of 160 cm from the ground

1. Minimum length of the mirror =80 cm
2. Minimum length of the mirror =85 cm
3. Bottom of the mirror should be at a height 80 cm
4. Bottom of the mirror should be at a height 85 cm

Q. What is the minimum length of the mirror required to visualise the complete image of the body of a person of height H.

1. Cannot be formed
2. 3H
3. $\frac{H}{2}$
4. $\frac{H}{3}$

Q. A boy of height $1.5m$ with his eye level at $1.4m$ stands before a plane mirror of length $0.75m$ fixed on the wall. The height of the lower edge of the mirror above the floor is $0.8m$. Then

1. the boy will see his full image
2. the boy cannot see his hair
3. the boy cannot see his feet
4. the boy can neither see his hair nor his feet

Q. The minimum length of a plane mirror required to view the full image of a person 6 feet tall is :

1. 3 feet
2. 5 feet
3. 6 feet
4. 4 feet