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All questions of Class 10 NCERT Physics for UPSC CSE Exam
We use __________ lens to correct Hypermetropia- a)Biconvex
- b)Biconcave
- c)Concave
- d)Convex
Correct answer is option 'D'. Can you explain this answer?
We use __________ lens to correct Hypermetropia
a)
Biconvex
b)
Biconcave
c)
Concave
d)
Convex
 | Anjali Kapoor answered |
Concave lenses are used here. They spread the light out before it reaches the convex lens in the eye, therefore letting the image focus directly on the retina. Hyperopia is known to you probably as farsightedness.
To get 2Ω resistance using only 6Ω resistors, the number of them required is- a)2
- b)3
- c)4
- d)6
Correct answer is option 'B'. Can you explain this answer?
To get 2Ω resistance using only 6Ω resistors, the number of them required is
a)
2
b)
3
c)
4
d)
6
| | Avinash Patel answered |
Three resistors of 2Ω is required to get 6Ω because resultant is more than individual so they all must be connected in series.
The effective resistance between A and B is
- a)4Ω
- b)6Ω
- c)May be 10Ω
- d)Must be 10Ω
Correct answer is option 'A'. Can you explain this answer?
The effective resistance between A and B is
a)
4Ω
b)
6Ω
c)
May be 10Ω
d)
Must be 10Ω
 | Gaurav Kumar answered |
6Ω is shorted
as current will pass from wire having no resistance
so effective resistance is 4Ω.
as current will pass from wire having no resistance
so effective resistance is 4Ω.
The potential difference of a circuit is constant. If the resistance of a circuit is doubled, then its current will become;- a)4 I
- b)I/2
- c)2 I
- d)I
Correct answer is 'B'. Can you explain this answer?
The potential difference of a circuit is constant. If the resistance of a circuit is doubled, then its current will become;
a)
4 I
b)
I/2
c)
2 I
d)
I
 | Nisha Choudhury answered |
According to ohm's law
Current (I) = Potential difference (V) / Resistance(R)
If the potential difference is maintained constant and the resistance is changed,
Cureent (I) is inversely proportinal to the reisistance (R)
V = IR --(1)
Now, here V is constant.
Let , new resistance R' = 2R and assume that current flow be I'
So, from (1),
IR = I'. R',
=> IR = I'. 2R,
Therefore, I' = I / 2
So,
If the resistance is doubled by applying the constant potential difference the current becomes the half of the previous.
Speed of light in vacuum is:- a)3 x 108 m/s
- b)3 x 109 m/s
- c)2 x 109 m/s
- d)2 x 1011 m/s
Correct answer is option 'A'. Can you explain this answer?
Speed of light in vacuum is:
a)
3 x 108 m/s
b)
3 x 109 m/s
c)
2 x 109 m/s
d)
2 x 1011 m/s
 | Krishna Iyer answered |
The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. It's exact value is defined as 299 792 458 metres per second ( or approximately, 3*108 m/s)
Calculate the current flows through the 10Ω resistor in the following circuit.
- a)1.2A
- b)0.6A
- c)0.2A
- d)2.0A
Correct answer is option 'B'. Can you explain this answer?
Calculate the current flows through the 10Ω resistor in the following circuit.
a)
1.2A
b)
0.6A
c)
0.2A
d)
2.0A
 | Sun Ray Institute answered |
In parallel, potential difference across each resistor will remain same. So, current through 10Ω resistor
The image formed on the retina of the human eye is- a)virtual and inverted
- b)real and inverted
- c)real and erect
- d)virtual and erect
Correct answer is option 'B'. Can you explain this answer?
The image formed on the retina of the human eye is
a)
virtual and inverted
b)
real and inverted
c)
real and erect
d)
virtual and erect
 | Pooja Shah answered |
Eye lens is convex, in nature. So, image formed by it on the retina is real and inverted.
Stars twinkle due to- a)atmospheric refraction
- b)atmospheric reflection
- c)scattering of light
- d)dispersion of light
Correct answer is option 'A'. Can you explain this answer?
Stars twinkle due to
a)
atmospheric refraction
b)
atmospheric reflection
c)
scattering of light
d)
dispersion of light
 | Deepika Shah answered |
The twinkling of a star is due to atmospheric refraction of starlight. The starlight, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth. The atmospheric refraction occurs in a medium of gradually changing refractive index. Since the atmosphere bends starlight towards the normal, the apparent position of the star is slightly different from its actual position.
The near point of a human eye is at a distance of- a)10 cm
- b)20 cm
- c)40 cm
- d)25 cm
Correct answer is option 'D'. Can you explain this answer?
The near point of a human eye is at a distance of
a)
10 cm
b)
20 cm
c)
40 cm
d)
25 cm
| | Abhi Prajapati answered |
The near point of the eye is the minimum distance of the object from the eye, which can be seen distinctly without strain. For a normal human eye, this distance is 25 cm. The far point of the eye is the maximum distance to which the eye can see the objects clearly. The far point of the normal human eye is infinity.
Ability of the eye to see objects at all distances is calleda)Binocular visionb)Myopiac)Accommodationd)HypermetropiaCorrect answer is option 'C'. Can you explain this answer?
 | Ishan Choudhury answered |
Changes in the contraction of the ciliary muscles alter the focal distance of the eye, causing nearer or future images to come into focus on the retina; this process is known as accommodation.
The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light- a)is scattered the most by smoke or fog
- b)is scattered the least by smoke or fog
- c)is absorbed the most by smoke or fog
- d)moves fastest in air
Correct answer is option 'B'. Can you explain this answer?
The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light
a)
is scattered the most by smoke or fog
b)
is scattered the least by smoke or fog
c)
is absorbed the most by smoke or fog
d)
moves fastest in air
| | Kiran Mehta answered |
Red colour has longer wavelength so least scattered by smoke or fog.
Cataract can be cured by- a)Bi-focal Lens
- b)Convex Lens
- c)Surgery
- d)Concave lens
Correct answer is option 'C'. Can you explain this answer?
Cataract can be cured by
a)
Bi-focal Lens
b)
Convex Lens
c)
Surgery
d)
Concave lens
 | Rohan Kapoor answered |
Surgery to treat cataracts involves removing the clouded lens and replacing it with a synthetic new one. This procedure is safe and very effective.They're researching eye drops that may dissolve cataracts so patients don't have to go to surgery.
If four resistors each of 1Ω are connected in parallel, the effective resistance will be- a)0.5Ω
- b)0.25Ω
- c)4Ω
- d)2Ω
Correct answer is option 'B'. Can you explain this answer?
If four resistors each of 1Ω are connected in parallel, the effective resistance will be
a)
0.5Ω
b)
0.25Ω
c)
4Ω
d)
2Ω
| | Gaurav Kumar answered |
If four resistors each of 1Ω are connected in parallel, the effective resistance will be 0.25Ω..
As, in parralel connection,
1/Reff. = 1/R1 + 1/R2 + ....
An object 2 cm high is placed at a distance of 15 cm from a concave mirror which produces an inverted image 4 cm high. Find the position of the image.- a)-30 cm
- b)30 cm
- c)40 cm
- d)-40 cm
Correct answer is option 'B'. Can you explain this answer?
An object 2 cm high is placed at a distance of 15 cm from a concave mirror which produces an inverted image 4 cm high. Find the position of the image.
a)
-30 cm
b)
30 cm
c)
40 cm
d)
-40 cm
| | Krishna Iyer answered |
The magnification produced by a concave mirror is given by the formula:
m = -v/u
where, m = magnification v = image distance u = object distance
From the problem, we have: u = -15 cm (since the object is placed in front of the mirror, the distance is negative) m = -4/2 = -2 (since the image is inverted and 4 cm high whereas the object is 2 cm high)
Substituting these values in the magnification formula, we get:
-2 = -v/(-15)
Simplifying, we get:
v = 30 cm
Therefore, the position of the image is 30 cm from the concave mirror.
The human eye forms the image of an object at its- a)Iris
- b)Pupil
- c)Cornea
- d)Retina
Correct answer is option 'D'. Can you explain this answer?
The human eye forms the image of an object at its
a)
Iris
b)
Pupil
c)
Cornea
d)
Retina
| | Rahul Kapoor answered |
Retina is the inner back portion of eye. Retina is composed of enormous number of light sensitive cells. Lens forms image of the visual world on retina through cornea. Light sensitive cells of retina get activated upon illumination and generate electric signals. Optic nerves send these electric signals to the brain, where these signals finally processed and interpreted to see an object as they are.
The water heating rod draws 10 A current when connected to certain power source. The resistance of rod is 12 Ω. The source voltage is:- a)1.2 V
- b)120 V
- c)1200 V
- d)None of these
Correct answer is option 'B'. Can you explain this answer?
The water heating rod draws 10 A current when connected to certain power source. The resistance of rod is 12 Ω. The source voltage is:
a)
1.2 V
b)
120 V
c)
1200 V
d)
None of these
| | Aditya Kumar answered |
The correct answer is B as Ohm's law:
voltage=current x resistance=12x10=120 V
voltage=current x resistance=12x10=120 V
A student sitting on last bench in a classroom cannot see clearly words written on the blackboard. He is suffering from- a)long sightedness
- b)short sightedness
- c)astigmatism
- d)long sightedness as well as short sightedness
Correct answer is option 'B'. Can you explain this answer?
A student sitting on last bench in a classroom cannot see clearly words written on the blackboard. He is suffering from
a)
long sightedness
b)
short sightedness
c)
astigmatism
d)
long sightedness as well as short sightedness
| | Amit Sharma answered |
A student, who cannot read words written on blackboard from the last bench of his class room, is suffering from the myopia or short-sightedness defect of vision of eye.
Conventional direction of electric current is from- a)Lower potential to higher potential
- b)Higher resistance to lower resistance
- c)Positive to negative terminal
- d)Negative to positive terminal
Correct answer is 'C'. Can you explain this answer?
Conventional direction of electric current is from
a)
Lower potential to higher potential
b)
Higher resistance to lower resistance
c)
Positive to negative terminal
d)
Negative to positive terminal
 | C K Academy answered |
The current in the wire is due to the drifting of electrons inside a wire in a direction opposite to the flow of electrons. During their drifting they collide with their atoms vibrating about their mean position and lose some of kinetic energy to the vibrating atoms.
The electrons are negatively charged particles and so, the electrons move towards the positively charged terminal from the negatively charged terminal.
Hence, the statement is true as the conventional direction of flow of current is from positive terminal to negative terminal of the cell.
The electrons are negatively charged particles and so, the electrons move towards the positively charged terminal from the negatively charged terminal.
Hence, the statement is true as the conventional direction of flow of current is from positive terminal to negative terminal of the cell.
Overloading is due to- a)Insulation of wire is damaged
- b)fault in the appliances
- c)accidental hike in supply voltage
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
Overloading is due to
a)
Insulation of wire is damaged
b)
fault in the appliances
c)
accidental hike in supply voltage
d)
All of the above
| | Rohit Sharma answered |
Overloading occurs when there is any fault in the appliances or the insulation of wire got damaged. It also occurs when there is sudden hike in supply voltage.
Which of the following phenomena of light are involved in the formation of a rainbow ?- a)Reflection, refraction and dispersion
- b)Refraction, dispersion and scattering
- c)Refraction, dispersion and internal reflection
- d)Dispersion, scattering and refraction
Correct answer is option 'C'. Can you explain this answer?
Which of the following phenomena of light are involved in the formation of a rainbow ?
a)
Reflection, refraction and dispersion
b)
Refraction, dispersion and scattering
c)
Refraction, dispersion and internal reflection
d)
Dispersion, scattering and refraction
| | Aditya Shah answered |
Phenomena of refraction, dispersion and internal reflection are involved in the formation of rainbow.
Can you explain the answer of this question below:The combination of a convex lens of power +2D and a concave lens of power -2D, acts as a
- A:
glass slab
- B:
bi-focal lens of power 0 D
- C:
prism
- D:
convex lens of power 0 D.
The answer is a.
The combination of a convex lens of power +2D and a concave lens of power -2D, acts as a
glass slab
bi-focal lens of power 0 D
prism
convex lens of power 0 D.
| | Gaurav Kumar answered |
Net power =0
F=infinity
The emergent ray in the rectangular glass slab is parallel to the incident ray so the focal length of the glass slab is infinite.
F=infinity
The emergent ray in the rectangular glass slab is parallel to the incident ray so the focal length of the glass slab is infinite.
The unit of linear magnification is- a)Dioptre
- b)Metre
- c)Metre per second
- d)It is unitless
Correct answer is option 'D'. Can you explain this answer?
The unit of linear magnification is
a)
Dioptre
b)
Metre
c)
Metre per second
d)
It is unitless
| | Gaurav Kumar answered |
Magnification is thr ratio of size of image to size of object and since it is a ratio of tel similar quantities hence it is unitless.
Can you explain the answer of this question below:How much work is done, when 1 coulomb of charge moves against a potential difference of 1 volt?
- A:
1 joule
- B:
2 joule
- C:
0.5 joule
- D:
1.5 joule
The answer is a.
How much work is done, when 1 coulomb of charge moves against a potential difference of 1 volt?
1 joule
2 joule
0.5 joule
1.5 joule
| | Arun Yadav answered |
Charge moved, Q = 1 C
Potential difference, V = 1V
Therefore,
Work done, W = QV
= 1 C x 1 V
= 1 joule.
A wire of resistance 8Ω is bent in the form of a closed circle. What is the effective resistance between the two points A and B, at the ends of any diameter of the circle ?
- a)8Ω
- b)4Ω
- c)2Ω
- d)1Ω
Correct answer is option 'C'. Can you explain this answer?
A wire of resistance 8Ω is bent in the form of a closed circle. What is the effective resistance between the two points A and B, at the ends of any diameter of the circle ?
a)
8Ω
b)
4Ω
c)
2Ω
d)
1Ω
 | Flembe Academy answered |
When a wire of 8Ω resistance is bent in the form of a closed circle, resistance of each half (semicircular) part is 8/2 Ω = 4Ω.
As these two parts are connected in parallel across points A and B, hence effective resistance will be 2Ω.
As these two parts are connected in parallel across points A and B, hence effective resistance will be 2Ω.
Earth wire carries- a)current
- b)voltage
- c)no current
- d)heat
Correct answer is option 'C'. Can you explain this answer?
Earth wire carries
a)
current
b)
voltage
c)
no current
d)
heat
| | Kiran Mehta answered |
A "grounding" wire on the other hand is a safety wire that has intentionally been connected to earth. The grounding wire does not carry electricity under normal circuit operations. It's purpose is to carry electrical current only under short circuit or other conditions that would be potentially dangerous.
The resistance whose V - I graph is given below is
- a)
- b)
- c)
- d)
Correct answer is option 'B'. Can you explain this answer?
The resistance whose V - I graph is given below is
a)
b)
c)
d)
 | Prachi shukla answered |
Resistance = slope line of V-I graph
When a beam of white light passes through a glass prism, it splits up into seven colours. This phenomenon is due to- a)refraction of light
- b)dispersion of light
- c)diffraction of light
- d)absorption of light
Correct answer is option 'B'. Can you explain this answer?
When a beam of white light passes through a glass prism, it splits up into seven colours. This phenomenon is due to
a)
refraction of light
b)
dispersion of light
c)
diffraction of light
d)
absorption of light
 | Kajal verma answered |
Splitting of white light into its constituent seven colours, while passing through a prism, is on account of dispersion of fight.
If the magnification has a negative sign, the image formed by the concave mirror must be- a)Real and inverted
- b)Virtual and inverted
- c)Virtual and erect
- d)Real and erect
Correct answer is option 'A'. Can you explain this answer?
If the magnification has a negative sign, the image formed by the concave mirror must be
a)
Real and inverted
b)
Virtual and inverted
c)
Virtual and erect
d)
Real and erect
| | Naina Sharma answered |
We know that, if the magnification value is negative sign in the concave mirror, then the image will be real and inverted. Especially, when you come to concave mirror, the images are formed at the left of the mirror. So, it forms real and inverted.
On a clear day, the sky appears to be more blue towards the zenith (overhead) than it does toward the horizon. This occurs because:- a)the atmosphere is denser higher up than it is at the earth’s surface.
- b)the temperature of the upper atmosphere is higher than it is at the earth’s surface.
- c)the sunlight travels over a longer path at the horizon, resulting in more absorption.
- d)none of the above is true.
Correct answer is option 'C'. Can you explain this answer?
On a clear day, the sky appears to be more blue towards the zenith (overhead) than it does toward the horizon. This occurs because:
a)
the atmosphere is denser higher up than it is at the earth’s surface.
b)
the temperature of the upper atmosphere is higher than it is at the earth’s surface.
c)
the sunlight travels over a longer path at the horizon, resulting in more absorption.
d)
none of the above is true.
| | Aditya Shah answered |
Because when the light of sun travel a long distance it meets with large amount of particles present in atmosphere. When they crush with small particles they got scattered due to which the blue color which have shorter wavelength, scatters most by which the sky seems blue.
The light coming from an object enters the eye through:- a)cornea and pupil
- b)Pupil and retina
- c)iris and pupil
- d)cornea and iris
Correct answer is option 'A'. Can you explain this answer?
The light coming from an object enters the eye through:
a)
cornea and pupil
b)
Pupil and retina
c)
iris and pupil
d)
cornea and iris
 | Vikas Kumar answered |
Light rays enter the eye through the cornea, the clear front “window” of the eye. The cornea's refractive power bends the light rays in such a way that they pass freely through the pupil the opening in the center of the iris through which light enters the eye.
A boy is wearing glasses and says that he cannot see the object kept at a distance without glasses. He is suffering from- a)Hypermetropia
- b)Cataract
- c)Presbyopia
- d)Myopia
Correct answer is option 'D'. Can you explain this answer?
A boy is wearing glasses and says that he cannot see the object kept at a distance without glasses. He is suffering from
a)
Hypermetropia
b)
Cataract
c)
Presbyopia
d)
Myopia
| | Raghav Bansal answered |
As Myopia is a defect of vision in which a person cannot see the distant object clearly. This can be corrected by using the concave lens of appropriate focal length
A resistance wire is stretched so as to double its length. Its new resistivity will have a magnitude- a)2 times its original value
- b)4 times its original value
- c)8 times its original valu
- d)same as its original value
Correct answer is option 'D'. Can you explain this answer?
A resistance wire is stretched so as to double its length. Its new resistivity will have a magnitude
a)
2 times its original value
b)
4 times its original value
c)
8 times its original valu
d)
same as its original value
| | Anita Menon answered |
When a wire is stretched, its resistivity remains unchanged. It is because resistivity of a conductor depends only on its material and is independent of its length or cross- section area.
What should be the core of an electromagnet?- a)soft iron
- b)hard iron
- c)rusted iron
- d)none of above
Correct answer is option 'A'. Can you explain this answer?
What should be the core of an electromagnet?
a)
soft iron
b)
hard iron
c)
rusted iron
d)
none of above
| | Chetna bhatia answered |
The core of an electromagnet should be a) soft iron.
Explanation: Soft iron is used as the core of an electromagnet because of its high magnetic permeability, meaning it can easily magnetize and demagnetize in response to an external magnetic field. When an electric current is passed through a coil wrapped around the soft iron core, it becomes strongly magnetized and creates a strong magnetic field. When the current is removed, the magnetism of the soft iron core quickly disappears, allowing the electromagnet to be turned on and off easily. Hard iron, on the other hand, retains its magnetism longer and is not suitable for electromagnets that need to be switched on and off frequently. Rusted iron is not ideal because the rust would interfere with the magnetic properties and reduce the efficiency of the electromagnet.
Explanation: Soft iron is used as the core of an electromagnet because of its high magnetic permeability, meaning it can easily magnetize and demagnetize in response to an external magnetic field. When an electric current is passed through a coil wrapped around the soft iron core, it becomes strongly magnetized and creates a strong magnetic field. When the current is removed, the magnetism of the soft iron core quickly disappears, allowing the electromagnet to be turned on and off easily. Hard iron, on the other hand, retains its magnetism longer and is not suitable for electromagnets that need to be switched on and off frequently. Rusted iron is not ideal because the rust would interfere with the magnetic properties and reduce the efficiency of the electromagnet.
All elements of an electric circuit are connected in series except :- a)voltmeter
- b)ammeter
- c)rheostat
- d)resistor
Correct answer is option 'A'. Can you explain this answer?
All elements of an electric circuit are connected in series except :
a)
voltmeter
b)
ammeter
c)
rheostat
d)
resistor
| | Ishan Choudhury answered |
In an electric circuit all other elements are connected in series but a voltmeter is connected in parallel.
A person with defective eyesight is unable to see objects clearly nearer than 1.5 m. He wants to read a book placed at a distance of 30 cm from his eyes. The type of a required lens and its focal length is- a)Concave lens, f = 37.5 cm
- b)Convex lens, f = 30.5 cm
- c)Convex lens, f = 37.5 cm
- d)Concave lens, f = 30.5 cm
Correct answer is option 'C'. Can you explain this answer?
A person with defective eyesight is unable to see objects clearly nearer than 1.5 m. He wants to read a book placed at a distance of 30 cm from his eyes. The type of a required lens and its focal length is
a)
Concave lens, f = 37.5 cm
b)
Convex lens, f = 30.5 cm
c)
Convex lens, f = 37.5 cm
d)
Concave lens, f = 30.5 cm
| | Rahul Kapoor answered |
This person suffers from the defect of hypermetropia.
For him u = -30cm, v = -1.5 m = -150cm
Therefore, focal length of corrective lens to be used by him is
1/f = 1/v- 1/u = 1/-150 - 1/-30 = 4/150 = 37.5cm
The positive sign shows that the lens needed is a convex lens of focal length 37.5 cm.
Hence, power of lens needed
P =1/f = 100/37.5 = 2.67D
Two devices are connected between two points say A and B in parallel. The physical quantity that will remain the same between the two points is- a)current
- b)voltage
- c)resistance
- d)None of these
Correct answer is option 'B'. Can you explain this answer?
Two devices are connected between two points say A and B in parallel. The physical quantity that will remain the same between the two points is
a)
current
b)
voltage
c)
resistance
d)
None of these
 | Meera Rana answered |
In parallel combination voltage remains same across two points.
The colour which deviates most in the formation of spectrum of white light by a prism is- a)Green
- b)Yellow
- c)Red
- d)Violet
Correct answer is option 'D'. Can you explain this answer?
The colour which deviates most in the formation of spectrum of white light by a prism is
a)
Green
b)
Yellow
c)
Red
d)
Violet
| | Rahul Kapoor answered |
When white light falls on a glass prism, each colour in it is refracted by a different angle, from which red colour is least deviated and violet most.
A bulb draws a current of 0.20 A for 15 minutes. What is the amount of electric charge that flows through it ?- a)180 C
- b)182 C
- c)200 C
- d)300 C
Correct answer is option 'A'. Can you explain this answer?
A bulb draws a current of 0.20 A for 15 minutes. What is the amount of electric charge that flows through it ?
a)
180 C
b)
182 C
c)
200 C
d)
300 C
| | Rajiv Gupta answered |
The amount of electric charge that flows through the bulb =180 C.
Can you explain the answer of this question below:A person having myopic eyes uses a concave lens of focal length 50 cm. What is the power of the lens?
- A:
+ 0.02 D
- B:
+ 2 D
- C:
– 0.02 D
- D:
– 2 D
The answer is d.
A person having myopic eyes uses a concave lens of focal length 50 cm. What is the power of the lens?
+ 0.02 D
+ 2 D
– 0.02 D
– 2 D
| | Raghav Bansal answered |
So focal length = - 50 cm = - 0.50 meter
power = - 1/0.50 = -2 Dioptre or - 2 D
power = - 1/0.50 = -2 Dioptre or - 2 D
A cooler of 1500 W, 200 volt and a fan of 500 W, 200 volt are to be used from a household supply. The rating of fuse to be used is- a)2.5 A
- b)5.0 A
- c)7.5 A
- d)10 A
Correct answer is option 'D'. Can you explain this answer?
A cooler of 1500 W, 200 volt and a fan of 500 W, 200 volt are to be used from a household supply. The rating of fuse to be used is
a)
2.5 A
b)
5.0 A
c)
7.5 A
d)
10 A
| | Shreyas murthy answered |
Total power used, P - P1 + P2 = 1500 + 500 = 2000 W.
Current drawn from the supply,
Current drawn from the supply,
The clear sky appears blue because- a)blue light gets absorbed in the atmosphere
- b)ultraviolet radiations are absorbed in the atmosphere
- c)violet and blue lights get scattered more than lights of all other colours by the atmosphere
- d)light of all other colours is scattered more than the violet and blue colour lights by the atmosphere
Correct answer is option 'C'. Can you explain this answer?
The clear sky appears blue because
a)
blue light gets absorbed in the atmosphere
b)
ultraviolet radiations are absorbed in the atmosphere
c)
violet and blue lights get scattered more than lights of all other colours by the atmosphere
d)
light of all other colours is scattered more than the violet and blue colour lights by the atmosphere
| | Kuldeep Kuldeep answered |
As the Sun is made up of all the colours, Sun scatters the colour having a shorter wavelength. Rather than other colours Violet and Blue having the shorter wavelength. So the Violet and Blue colour lights get scattered more than lights of all other colours by the atmosphere. So, option c is correct friend...
A combination of three resistances has been shown here. Effective resistance between the points A and B is
- a)8Ω
- b)4Ω
- c)2Ω
- d)1Ω
Correct answer is option 'C'. Can you explain this answer?
A combination of three resistances has been shown here. Effective resistance between the points A and B is
a)
8Ω
b)
4Ω
c)
2Ω
d)
1Ω
| | Pooja Shah answered |
Value of series combination of 2Ω and 2Ω resistances = 4Ω. As it is now connected in parallel to 4Ω resistance, hence the effective resistance R between the points A and B will be
In Fleming’s left-hand rule the thumb indicates the direction of- a)magnetic field applied
- b)current flown in the conductor
- c)induced current
- d)mechanical force on the conductor
Correct answer is option 'D'. Can you explain this answer?
In Fleming’s left-hand rule the thumb indicates the direction of
a)
magnetic field applied
b)
current flown in the conductor
c)
induced current
d)
mechanical force on the conductor
| | Krishna Iyer answered |
In Fleming’s left-hand rule the thumb indicates the direction of mechanical force acting on the conductor. The forefinger points in the direction of magnetic field and the central finger in the direction of current flowing in the conductor.
Can you explain the answer of this question below:Light travels faster in substance X as compared to substance Y, then refractive index is greater for
- A:
Can’t tell with the information provided
- B:
Substance-Y
- C:
Refractive index for both is same
- D:
Substance-X
The answer is b.
Light travels faster in substance X as compared to substance Y, then refractive index is greater for
Can’t tell with the information provided
Substance-Y
Refractive index for both is same
Substance-X
| | Gaurav Kumar answered |
As the refractive index increases, the velocity of light decreases.
The air layer of atmosphere whose temperature is less than the hot layer behave as optically- a)denser medium
- b)rarer medium
- c)inactive medium
- d)either denser or rarer medium
Correct answer is option 'A'. Can you explain this answer?
The air layer of atmosphere whose temperature is less than the hot layer behave as optically
a)
denser medium
b)
rarer medium
c)
inactive medium
d)
either denser or rarer medium
| | Anita Menon answered |
The cold air layer of the atmosphere acts as a optically denser medium than hot air because the molecules are closely packed together.
SI unit of resistivity is- a)ohm/metre
- b)ohm-metre
- c)ohm/(metre)3
- d)ohm/(metre)2
Correct answer is option 'B'. Can you explain this answer?
SI unit of resistivity is
a)
ohm/metre
b)
ohm-metre
c)
ohm/(metre)3
d)
ohm/(metre)2
| | Krishna Iyer answered |
As resistivity of the material of a resistor of length l, cross-section area A and resistance R is given by :ρ = R.A/I, hence SI unit of resistivity is ohm -metre (Ω m).
The opposing capacity of materials against the current flow is- a)Conductance
- b)Inductance
- c)Susceptance
- d)Resistance
Correct answer is option 'D'. Can you explain this answer?
The opposing capacity of materials against the current flow is
a)
Conductance
b)
Inductance
c)
Susceptance
d)
Resistance
 | Crafty Classes answered |
The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor.
Resistance in a conductor can be defined as the opposition offered to the flow of electrons. For a conductor of uniform cross-sectional area resistance is directly proportional to the length of the conductor and inversely proportional to the cross-sectional area of the conductor.
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