Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

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.

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

Light has a wave nature,because-

  1. The light travel in a straight line

  2. Light exhibits phenomenon of reflection and refraction

  3. Lights phenomeno interference

  4. Light exhibits phenomeno of photo electric effect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Wave nature of light is demonstrated by wave phenomena like interference, diffraction, and polarization. Interference (superposition of waves creating patterns of constructive and destructive interference) cannot be explained by particle theory. Photoelectric effect (option D) demonstrates particle nature, not wave nature. Reflection and refraction can be explained by both theories.

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

Which one statement is correct -

  1. Speed of light in free space $= \frac{1}{\sqrt{\mu _0 \varepsilon _0}}$

  2. Speed of light in any medium $=\frac{1}{\sqrt{\mu \varepsilon}}$

  3. $\frac{E _0}{B _0}=2C$

  4. $\frac{B _0}{E _0}=4C$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The speed of light in free space is given by c = 1 / sqrt(mu_0 * epsilon_0), which is a fundamental result of Maxwell's equations.

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

Light falls on a plane reflecting surface. For what angle of incidence is the reflected ray normal to the incident ray. 

  1. $60^o$

  2. $45^o$

  3. $90^o$

  4. $30^o$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The incident ray will have an angle of reflection of ${30^0}$ $($made with a surface normal to the mirror surface$).$

Hence,
option $(D)$ is correct answer.

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

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 

  1. All are correct

  2. $I, II$ are correct

  3. $II, III$ are correct

  4. $I, III $are correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All statements are correct: a large hole causes blurring (Statement I), increasing object distance decreases image size (Statement II), and increasing screen distance makes the image larger but dimmer/blurred (Statement III).

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

State the effect on the image formed by a pinhole camera if the size of the hole is increased.

  1. The image becomes blurred

  2. The image gets sharper

  3. The image completely vanishes

  4. No image is formed to begin with
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If the size of the hole increases the image will be blurred as several 
images are formed which overlap each other

Multiple choice particles of a gas ideal gases physics

Motion of molecule in a substance is concluded by

  1. Using microscopes

  2. Mathematical postulates

  3. Using assumptions

  4. Observations from experiments
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Molecules are too small to be seen by microscope. Motion of molecules can be concluded by observations seen in experiment,such as diffusion of ink particles in water,light scattering experiments etc.