Tag: evs

Questions Related to evs

The illumination on the screen, in case of a movie hall if the distance between the projector and the screen is increased by $1\%$ will be:

evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

  1. increased by $1\%$

  2. decreased by $1\%$

  3. increased by $2\%$

  4. decreased by $2\%$

Show answer
Correct Option: D
Explanation:

Projector act as a point source

Hence   $E\propto \dfrac{1}{r^{2}}$
$\dfrac{dE}{E}=2\left(\dfrac{\Delta r}{r}\right)=2\times 1\%=2\%$
As the distance increases, the illumination will decrease.

Pick the only wrong statement in the following :

evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

  1. Light travels with a speed greater than that of sound

  2. Light cannot travel through vacuum

  3. Light travels in a straight line

  4. Light is a wave motion

Show answer
Correct Option: B
Explanation:

Light travels through vacuum for sure as it does not need a material medium for its propagation. Sunlight is the biggest example for this.

Moreover, light has maximum speed in vacuum ,that is, $3\times 10^8$.

A broader bundle of light rays is called a -

evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

  1. Beam of light

  2. Ray of light

  3. Bundle of light

  4. None of these

Show answer
Correct Option: A
Explanation:

A single wave of light is called a ray.

Bundle of light rays is called beam of light.

What is the wavelength range of visible light?

evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

  1. $ 4 \times 10^{-7} m $ to $ 8 \times 10^{-7} m$

  2. $ 4 \times 10^{-9} m $ to $ 8 \times 10^{-9} m$

  3. $ 4 \times 10^{-5} m $ to $ 8 \times 10^{-5} m$

  4. $ 4 \times 10^{-6} m $ to $ 8 \times 10^{-6} m$

Show answer
Correct Option: A
Explanation:

The wavelength of visible light lies between $400\,{\rm{nm}}$ to $800\,{\rm{nm}}$.

Or, $4 \times {10^{ - 7}}$ to $8 \times {10^{ - 7}}\,{\rm{m}}$

 

In a YDSE with two identical slits, when the upper slit is covered with a thin, perfectly transparent sheet of mica, the intensity at the centre of screen reduces to $75\%$ of the initial value. Second minima is observed to be above this point and third maxima below it. Which of the following can be a possible value of phase difference caused by the mica sheet.

evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

  1. $\dfrac{\pi}{3}$

  2. $\dfrac{13\pi}{3}$

  3. $\dfrac{17\pi}{3}$

  4. $\dfrac{11\pi}{3}$

Show answer
Correct Option: D
Explanation:

Here when second order minica replaces bright spot change in path difference$3\pi $


Second order minica phase difference$\dfrac { \pi  }{ 2 } $

Phase difference lies between $3\pi\ to\ 4\pi $ i.e. $\dfrac{11\pi}{3}$

Which of the following is the vegetative part of Jasmine plant?

evs seed becomes plant other modes of vegetative propagation the journey of seeds introduction to reproduction

  1. Stem

  2. Root

  3. Flower

  4. Leaf

Show answer
Correct Option: A
Explanation:

Jasmine grows from their branches cut and planted by the branch touching the soil developing roots and growing into a separate plant independent of the mother plant.

So the correct option is 'Stem'.

Asexual reproduction is related to

evs seed becomes plant other modes of vegetative propagation the journey of seeds introduction to reproduction

  1. Amphimixis

  2. Agamospermy

  3. Vegetative propagation

  4. Both B and C

Show answer
Correct Option: D
Explanation:
There are two modes of reproduction in plants: Sexual reproduction and Asexual reproduction. 
In sexual reproduction, there is the fusion of gametes of two different parents (called as syngamy) whereas, in sexual reproduction, offspring is formed from a single parent without the formation of gametes. Amphimixis is a kind of sexual reproduction which involves the meiosis and syngamy. A special type of asexual reproduction is there which is known as Apomixis in which there is seed formation without the fusion of gametes. Apomixis is further divided into two categories: Vegetative propagation and agamospermy. In vegetative propagation, any part of the plant may develop into a new plant. In agamospermy, plant propagation occurs by means of apomictic seeds or asexual seeds. 
Therefore, both vegetative propagation and agamospermy are types of asexual reproduction.
So, the correct answer is D.

Flowering plants are called as

evs seed becomes plant other modes of vegetative propagation the journey of seeds introduction to reproduction

  1. Angiosperms

  2. Gymnosperms

  3. Ferns

  4. Mosses

Show answer
Correct Option: A
Explanation:
Usually, angiosperms have flowers and bear fruits hence they are called flowering plants.

So, the correct answer is 'Angiosperms'.

Why seed dispersal is important?

evs seed becomes plant other modes of vegetative propagation the journey of seeds introduction to reproduction

  1. Survival of plant

  2. Introduction of plant

  3. Adaptation of plant

  4. None of these

Show answer
Correct Option: A
Explanation:

  • Dispersal of seed is important as if seeds germinate near to parent plants it will increase a lot of competition for air, water, and food as well. 
  • If competition increases it will lead to the death of the species and dispersal also leads to exposure to a new environment that helps in adaptation and evolution.

So, the correct option is 'Survival of plant'.

Seeds tarvel with water is filled with

evs seed becomes plant other modes of vegetative propagation the journey of seeds introduction to reproduction

  1. Water

  2. Air

  3. Protein

  4. None of the above

Show answer
Correct Option: B
Explanation:

Seeds that travel in water is modified certain mechanism that make them light and filled with air so that they are able to travel a long distance and reach to places that are far from the parents. Its best example is the modification of mesocarp of coconut that helps it in hydrochory and able it to float a long distance.

So, the correct option is 'Air'