Tag: formation of image by a pinhole camera

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Questions Related to formation of image by a pinhole camera

Multiple choice physics light and shadow formation of image by a pinhole camera pinhole camera shadow

Shadow formation is an example of :

  1. rectilinear propagation of light

  2. curvilinear propagation of light

  3. dispersion of light 

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rayleigh Scattering is responsible for the formation of shadows which is phenomena of rectilinear propagation of light . Shadows are created when an object, animal or person blocks out a portion of a light source. Shadows form in the opposite direction of whatever is blocking that source.

Multiple choice physics light, shadows and images formation of image by a pinhole camera pinhole camera shadow

What is "Camera Obscura" effect ?

  1. Light from a scene passes through the aperture and gets reflected from the mirror placed at the other end of the box.

  2. Light from a scene passes from one medium to another and gets refracted

  3. Light from a scene passes through the aperture and passes through a lens placed on the opposite side of the box

  4. Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A pinhole camera is a simple camera without a lens but with a tiny aperture, a pinhole – effectively a light-proof box with a small hole in one side. Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box, which is known as the camera obscura effect.

Multiple choice physics light and shadow formation of image by a pinhole camera pinhole camera shadow

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 $\sin \ 53^\circ = 0.8$]

  1. $15^\circ$

  2. $127^\circ$

  3. $138^\circ$

  4. $30^\circ$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The angle between the incoming and outgoing ray is $180^o-53=127$.

Multiple choice physics light and shadow formation of image by a pinhole camera pinhole camera shadow

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 :

  1. $18\pi\ m/s$

  2. $36\pi\ m/s$

  3. $72\pi\ m/s$

  4. $144\pi\ m/s$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When plane mirror rotates through an angle $\theta$ , the reflected ray rotates through an angle 2$\theta$. So spot on the screen will make 2 x 12 = 24  revolution per second.

 
To find the velocity 
v=2$\pi$R x frequency 
=2$\pi$ x 3 x 24
=144$\pi$ m/s

 D is the Correct answer.
 

Multiple choice physics light and shadow formation of image by a pinhole camera pinhole camera shadow

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

  1. $2.5\ units$

  2. $6\ units$

  3. $80\ units$

  4. $5\ units$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Intensity follows the inverse square law, I proportional to 1/r^2. If distance doubles from 2m to 4m, intensity becomes 1/4 of the original value: 20 / 4 = 5 units.