Tag: physics

Questions Related to physics

The force acting on a window of area 50 cm x 50 cm of a submarine at a depth of 2000 m in an ocean, the interior of which is maintained at sea level atmospheric pressure is (Density of sea water = 10$^3$ kg m$^{-3}$,g = 10 m s$^{-2}$)

physics floating bodies pressure exerted by a liquid column pressure at a certain depth in liquid variation of pressure with depth

  1. 5 x 10$^5$ N

  2. 25 x 10$^5$ N

  3. 5 x 10$^6$ N

  4. 25 x 10$^6$ N

Show answer
Correct Option: C
Explanation:

Here, $h = 2000 m,$

          $ \rho= 10^3\, kg\, m^{-3},$ 
          $g = 10 \,m \,s^{-2}$
The pressure outside the submarine is
$P = P _a + \rho gh$
where $P _a$ is the atmospheric pressure. Pressure inside the submarine is $P _a$.
Hence, net pressure acting on the window is gauge pressure. Gauge pressure,
 $P _g = P - P _a = \rho gh $
$= 10^3\, kg\, m^{-3} \times 10 \,m\,s^{-2} \times 2000 \,m$
$ = 2 \times 10^7 Pa$
Area of a window is $A= 50 cm\times50 cm $
                                    $= 2500 \times 10^{-4}\, m^{2}$
Force acting on the window is
$F = P _gA $
$= 2 \times 10^7 \,Pa \times 2500 \times 10^{-4} m^2 $
$= 5 \times 10^6\,N$

The whitish part of eye mainly:

physics option c: imaging human eye and its working what is inside our eyes? human eye and defects of vision

  1. provides characteristic colour to the eye

  2. acts as protective layer for the eye

  3. regulates the amount of light entering into the eye

  4. perceives the sensations

Show answer
Correct Option: B
Explanation:

Whitish part of eye is tough so that it can protect the eye from injuries.

It is white and transparent coat, known as cornea.

Which of the following part protects the eye and gives it shape?

physics human eye and colourful world human eye and its working what is inside our eyes? human eye and defects of vision

  1. Choroid

  2. Sclera

  3. Yellow spot

  4. Ciliary muscles

Show answer
Correct Option: B
Explanation:

Sclera protects the eye and gives it shape.

We are able to see objects around us because :

physics human eye and colourful world human eye and its working what is inside our eyes? human eye and defects of vision

  1. The objects absorb all the light.

  2. The light reflected from the object enters our eyes.

  3. Light can be refracted.

  4. Light travels in straight lines.

Show answer
Correct Option: B
Explanation:

We are able to see objects around us because the light reflected from the object enters our eyes.

Which of the following statements about human eye is not true?

physics human eye and colourful world human eye and its working what is inside our eyes? human eye and defects of vision

  1. The iris gives a distinct colour to the eye

  2. The yellow spot is extremely sensitive to light

  3. The space between lens and cornea is filled with ciliary muscles

  4. The optic nerves enters the eye near the blind spot

Show answer
Correct Option: C
Explanation:

The iris gives a distinct colour to the eye is false.
The yellow spot is extremely sensitive to light is false.
The space between lens and cornea is filled with ciliary muscles is true.
The optic nerves enters the eye near the blind spot is false.

A series of fast moving still pictures can create an illusion of movement because :

physics human eye and colourful world human eye and its working what is inside our eyes? human eye and defects of vision

  1. The eye can focus on very rapidly changing pictures

  2. Eye is quicker than the brain

  3. Eye can separate two images only when the interval of separation between them is one-tenth of a second

  4. The optical cortex can see through the rapidly moving images.

Show answer
Correct Option: C
Explanation:

Human brain needs some time to process the images. It has the ability to see two distinct images only if the separation between them is one-tenth of a second, otherwise an illusion of continuity is created.

Power of accommodation of eye implies :

physics vision and the world of colours human eye and its working what is inside our eyes? human eye and defects of vision

  1. Control intensity

  2. Prevent internal reflection of light

  3. Change of focal length of eye lens

  4. all the above

Show answer
Correct Option: C
Explanation:

Power of accommodation of an eye is the ability of ciliary muscles to change the focal length of an eye (lens) to focus clearly the image on retina

Fill in the blank spaces by choosing the correct words from the list given below:
List : yellow spot, principal focus, less, shutter, more.

The small but very light sensitive area on the retina is called __________.

physics vision and the world of colours human eye and its working what is inside our eyes? human eye and defects of vision

  1. yellow spot

  2. principal focus

  3. shutter

  4. none of the above

Show answer
Correct Option: A
Explanation:

Yellow spot
Yellow spot is near the center of the retina and a highly pigmented area which is very sensitive to light.

State whether true or false:

Blind spot is found in the eyes of a blind person only.

physics vision and the world of colours human eye and its working what is inside our eyes? human eye and defects of vision

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Blind spot, small portion of the visual field of each eye that corresponds to the position of the optic disk (also known as the optic nerve head) within the retina. There are no photoreceptors in the optic disk, and, therefore, there is no image detection in this area. Every human has a blind spot.

Thus the above statement is false.

A cubical vessel sealed vessel with edge $L$ is placed on a cart, which is moving horizontally with an acceleration `a' as shown iin figure. The cube is filled with an ideal fluid having density $\rho$. Find the gauge pressure at the centre of the cubical vessel.

physics pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $\dfrac{Ldg}2$

  2. $\dfrac{Ld(g+a)}2$

  3. $\dfrac{Lda}2$

  4. $\dfrac{Ld(g-a)}2$

Show answer
Correct Option: B