Light : reflection and refraction from plane surface - class-VIII
Tests understanding of light properties including rectilinear propagation, pinhole camera principles, wave nature of light, reflection from plane surfaces, and basic light physics concepts for class VIII.
Questions
Shadow formation is an example of :
- rectilinear propagation of light
- curvilinear propagation of light
- dispersion of light
- none of these
Select the odd one out (shadows, eclipses, expansion, images)
- expansion
- shadows
- eclipses
- images
- True
- False
- True
- False
Beam of light incident on a plane forms a real image of reflection. The incident beam is:
- Parallel
- Convergent
- Divergent
- None of the above
What kind of lens is used in making a pinhole camera ?
- Concave lens
- Convex lens
- Concavo-convex lens
- No lens is used
What is "Camera Obscura" effect ?
- Light from a scene passes through the aperture and gets reflected from the mirror placed at the other end of the box.
- Light from a scene passes from one medium to another and gets refracted
- Light from a scene passes through the aperture and passes through a lens placed on the opposite side of the box
- Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box
A ray of sunlight enters a spherical water droplet $(n = \dfrac{4}{3})$ at an angle of incidence $53^\circ$ measured with respect to the normal to the surface. It is reflected from the back surface of the droplet and re-enters into air. The angle between the incoming and outgoing ray is [Take $\sin \ 53^\circ = 0.8$]
- $15^\circ$
- $127^\circ$
- $138^\circ$
- $30^\circ$
A small plane mirror kept at the centre of a sphere of diameter $3\ m$, makes $12$ revolution per second. A thin light beam is made incident on the mirror. The linear speed of the light spot on the sphere, formed after reflection from the mirror is :
- $18\pi\ m/s$
- $36\pi\ m/s$
- $72\pi\ m/s$
- $144\pi\ m/s$
Intensity of light due to a point source at a distance $2m$ is $20$ units. The intensity due to the same source at a distance of $4m$ is
- $2.5\ units$
- $6\ units$
- $80\ units$
- $5\ units$
Light has a wave nature,because-
- The light travel in a straight line
- Light exhibits phenomenon of reflection and refraction
- Lights phenomeno interference
- Light exhibits phenomeno of photo electric effect
Which one statement is correct -
- Speed of light in free space $= \frac{1}{\sqrt{\mu _0 \varepsilon _0}}$
- Speed of light in any medium $=\frac{1}{\sqrt{\mu \varepsilon}}$
- $\frac{E _0}{B _0}=2C$
- $\frac{B _0}{E _0}=4C$
Light falls on a plane reflecting surface. For what angle of incidence is the reflected ray normal to the incident ray.
- $60^o$
- $45^o$
- $90^o$
- $30^o$
Choose the correct option from the following
$ Statement I:$ If the size of the hole in a pinhole camera is as big as the size of a green gram then the image becomes thick and the details of the image are not clearly seen.
$Statement II:$ If the distance of the object from pinhole camera is increased then the size of the image that is observed on the screen also increases.
$Statement III :$ If the distance between screen and hole in the pinhole camera is increasing we observe the image is becoming blurred
- All are correct
- $I, II$ are correct
- $II, III$ are correct
- $I, III $are correct
The speed of light in air is ___________ m/s.
- $3$
- $3\times { 10 }^{ -5 }$
- $3\times { 10 }^{ 8 }$
- $3\times { 10 }^{ 10 }$
The Image formed in a pinhole camera is real.
- True
- False
State the effect on the image formed by a pinhole camera if the size of the hole is increased.
- The image becomes blurred
- The image gets sharper
- The image completely vanishes
- No image is formed to begin with