Image formation by plane mirror - class-X
Image formation by plane mirror
Questions
In case of reflection by a plane mirror, which of the following statement are not correct?
- It can never give real image
- It can never give inverted image
- It changes left into right
- It changes front into back
An object is placed symmetrically between the two plane mirrors inclined at angle of $30^o$. Then the total number of images formed is:
- 12
- 2
- 11
- 15
It is necessary to illuminate the bottom of a well by reflected solar beam when the light is incident at an angle of $\alpha = {40}^{\circ}$ to the vertical. At what angle $\beta$ to the horizontal should a plane mirror be placed?
- ${70}^{\circ}$
- ${20}^{\circ}$
- ${50}^{\circ}$
- ${40}^{\circ}$
Which of the following is a reflector of light?
- Sun
- Moon
- Star
- Filament
A plane mirror is in a vertical plane and is rotating about a vertical axis at 100 mm horizontal beam of light is incident on the mirror. The reflected beam will rotate at
- $100 rpm$
- $141 rpm$
- $0 rpm$
- $200 rpm$
When a mirror is rotated through an angle, the reflected ray moves through double that angle, the instrument based on the above principle is :
- Periscope
- Odometer
- Refractometer
- Sextant
A source of light lies on the angle bisector of two plane mirrors inclined at an angle $\theta$. The values of $\theta$, so that the light reflected from one mirror does not reach the other mirror will be
- $\theta \geq 120^0$
- $\theta \geq 90^0$
- $\theta \leq 120^0$
- $\theta < 30^0$
In a Michelson experiment for measuring speed of light, the distance traveled by light between two reflections from the rotating mirror is 4.8 km. The rotating mirror has a shape of a regular octagon. At what minimum angular speed of the mirror (other than zero) the image is formed at the position where a non-rotating mirror forms it?
- $780$ $rev/s$
- $7800$ $rev/s$
- $690$ $rev/s$
- $7500$ $rev/s$
A plane mirror which rotates $10^4$ times per minute reflects light on to a stationary mirror $50$ m away. This mirror reflects the light normally so that it strikes the rotating mirror again. The image observed in the rotating mirror is shifted through $2.4$ minutes from the position it occupies. When the rotating mirror is stationary, what is the speed of light?
- $3\times 10^8$ m/s
- $4\times 10^8$ m/s
- $5\times 10^8$ m/s
- $6\times 10^8$ m/s
A flat mirror revolves at a constant angular velocity making $n=0.4$ revolutions per second. With what velocity (in $ms^{-1}$ ) will a light spot move along a spherical screen with a radius of $15$ metres, if the mirror is at the centre of curvature of the screen?
- $37.7$
- $60.3$
- $68.7$
- $75.4$
- $90.4$
Light incident on a rotating mirror M is returned to a fixed mirror N placed 22.5 km away from M. The fixed mirror reflects it back to M (along the same path) which in turn reflects the light again along a direction that makes an angle of $\displaystyle { 27 }^{ o }$ with the incident direction. The speed of rotation of the mirror is:
- 250 revolutions $\displaystyle { s }^{ -1 }$
- 500 revolutions $\displaystyle { s }^{ -1 }$
- 1000 revolutions $\displaystyle { s }^{ -1 }$
- 125 revolutions $\displaystyle { s }^{ -1 }$
The reflective surface is given by y $=$ 2 sinx. The reflective surface is facing positive x-axis. What is the least values of co ordinate of the point where a ray parallel to positive x axis becomes parallel to positive y axis after reflection 2.
- $\left ( \dfrac{\pi }{3},\sqrt{3} \right )$
- $\left ( \dfrac{\pi }{2},\sqrt{2} \right )$
- $\left ( \dfrac{\pi }{3},\sqrt{2} \right )$
- $\left ( \dfrac{\pi }{4},\sqrt{2} \right )$
The angle between the incident and reflected rays is $90^o$. If the plane mirror is rotated by $10^o$ about O in the anti-clockwise direction in the plane perpendicular to the mirror, then the angle between the incident and reflected rays will be _______$^0$.
- 70
- 100
- 90
- 110
- 80
When a plane mirror is rotated through an angle $\theta$, the reflected ray rotates through an angle $2\theta$. Then the size of the image
- is halved
- is doubled
- remains unchanged
- is quadrupled