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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 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)
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.
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.
Can you explain the answer of this question below:Electric current always flows
- A:
Either lower to higher or higher to lower
- B:
At same potential
- C:
From lower to higher potential
- D:
From higher to lower potential
The answer is d.
Electric current always flows
Either lower to higher or higher to lower
At same potential
From lower to higher potential
From higher to lower potential
|
Raksha Chopra answered |
Electrons move from low potential to high potential. The direction of electric current is opposite to the direction of flow of electrons.
Hence Electric current always flows from higher to lower potential.
An electric motor converts- a)mechanical energy into electrical energy
- b)electrical energy into sound energy
- c)electrical energy into mechanical energy
- d)mechanical energy into sound energy
Correct answer is option 'C'. Can you explain this answer?
An electric motor converts
a)
mechanical energy into electrical energy
b)
electrical energy into sound energy
c)
electrical energy into mechanical energy
d)
mechanical energy into sound energy
|
|
Krishna Iyer answered |
An electric motor converts electrical energy into mechanical energy.
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.
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.
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.
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.
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.
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 device used to produce an electric current in a circuit is called- a)galvanometer
- b)electric generator
- c)electric motor
- d)inverter
Correct answer is option 'B'. Can you explain this answer?
The device used to produce an electric current in a circuit is called
a)
galvanometer
b)
electric generator
c)
electric motor
d)
inverter
|
|
Amit Sharma answered |
An electric generator is used to produce an electric current in a circuit.
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 + ....
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
|
|
Babli Singh answered |
A is correct because blackboard are not long distance
from the last students
from the last students
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.
The least resistance obtained by using 2Ω , 4Ω, 1Ω and 100Ω is
- a)< 100 Ω
- b)< 1 Ω
- c)< 4 Ω
- d)> 2 Ω
Correct answer is option 'C'. Can you explain this answer?
The least resistance obtained by using 2Ω , 4Ω, 1Ω and 100Ω is
a)
< 100 Ω
b)
< 1 Ω
c)
< 4 Ω
d)
> 2 Ω
|
|
Avinash Patel answered |
In parallel combination, the equivalent resistance is Smaller than the least resistance used in the circuit.
1/1+1/2+1/4+1/100 = 1.76
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.
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.
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.
The phenomenon of electromagnetic induction is
a) the process of charging a bodyb) the process of generating magnetic field due to current passing through a coilc) the process of producing induced current in a coil on changing magnetic field around it
d) the process of rotating a coil of an electric motor
Correct answer is option 'C'. Can you explain this answer?
c) the process of producing induced current in a coil on changing magnetic field around it
d) the process of rotating a coil of an electric motor
Correct answer is option 'C'. Can you explain this answer?
d) the process of rotating a coil of an electric motor
Correct answer is option 'C'. Can you explain this answer?
|
|
Amit Kumar answered |
Electromagnetic induction is the phenomenon due to which an induced current is set up in a coil when magnetic field around it, is changed.
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.
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.
What is the kilowatt-hour consumption of a 40 W lamp if it remains on for 1750 h ?- a)43.75
- b)70
- c)43,750
- d)70,000
Correct answer is option 'B'. Can you explain this answer?
What is the kilowatt-hour consumption of a 40 W lamp if it remains on for 1750 h ?
a)
43.75
b)
70
c)
43,750
d)
70,000
|
Pranavi Joshi answered |
1 KW/1000 W = 40 W/ x W.
Solve for x and you'll get the number of watts.
x= 40 w * 1750 hr ( the hrs that the lamp remain on).
= 70 Whr.
Two resistors are connected in series gives an equivalent resistance of 10Ω. When connected in parallel, gives 2.4Ω. Then the individual resistance are
- a)each of 5Ω
- b)6Ω and 4Ω
- c)7Ω and 4Ω
- d)8Ω and 2Ω
Correct answer is option 'B'. Can you explain this answer?
Two resistors are connected in series gives an equivalent resistance of 10Ω. When connected in parallel, gives 2.4Ω. Then the individual resistance are
a)
each of 5Ω
b)
6Ω and 4Ω
c)
7Ω and 4Ω
d)
8Ω and 2Ω
|
|
Rohit Sharma answered |
In series, Rs = R1 + R2 = 1OΩ
In parallel,
R1R2=12/5
R1+R2
R1R2=12/5x(R1+R2)
R1R2=12/5x10
R1R2=24
so option (B) fits these two equation very well
In parallel,
R1R2=12/5
R1+R2
R1R2=12/5x(R1+R2)
R1R2=12/5x10
R1R2=24
so option (B) fits these two equation very well
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
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.
Which among of these are the main characteristics of fuse element?- a)High conductivity
- b)low melting point
- c)do not burn due to oxidation
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
Which among of these are the main characteristics of fuse element?
a)
High conductivity
b)
low melting point
c)
do not burn due to oxidation
d)
All of the above
|
|
Amit Sharma answered |
Fuse wire must have high conductivity, low melting point and it do not burn due to oxidation. These characteristics of a fuse wire make it possible to prevent from damages.
The direction of induced current produced in a rectangular coil, when it is rotated in a uniform magnetic field, is given by- a)Fleming’s right-hand rule
- b)Fleming’s left-hand rule
- c)Ampere’s rule
- d)Right-hand thumb rule
Correct answer is option 'A'. Can you explain this answer?
The direction of induced current produced in a rectangular coil, when it is rotated in a uniform magnetic field, is given by
a)
Fleming’s right-hand rule
b)
Fleming’s left-hand rule
c)
Ampere’s rule
d)
Right-hand thumb rule
|
|
Arun Sharma answered |
Fleming’s right-hand rule gives the direction of induced current in a rectangular coil when the coil is rotated in a uniform magnetic field.
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
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.
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.
What is that instrument which can detect the presence of electric current in a circuit?- a)galvanometer
- b)motor
- c)generator
- d)none of above
Correct answer is option 'A'. Can you explain this answer?
What is that instrument which can detect the presence of electric current in a circuit?
a)
galvanometer
b)
motor
c)
generator
d)
none of above
|
|
Giriselvan Sridhar answered |
Ammeter also detects and measures current. But galvonometer only detects the current.
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
|
|
Rahul Kapoor answered |
The flow of electrons is termed electron current. Electrons flow from the negative terminal to the positive. Conventional current or simply current, behaves as if positive charge carriers cause current flow. Conventional current flows from the positive terminal to the negative.
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.
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.
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).
Which method can be used for absolute measurement of resistances ?- a)Ohm's law method
- b)Wheatstone bridge method
- c)Releigh method
- d)Lortentz method.
Correct answer is option 'B'. Can you explain this answer?
Which method can be used for absolute measurement of resistances ?
a)
Ohm's law method
b)
Wheatstone bridge method
c)
Releigh method
d)
Lortentz method.
|
Anoushka Nambiar answered |
Wheat stone bridge method
A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide extremely accurate measurements.
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.
A coil in the heater consume power P on passing current. If it is cut into halves and joined in parallel, it will consume power- a)P
- b)P/2
- c)2P
- d)4P
Correct answer is option 'D'. Can you explain this answer?
A coil in the heater consume power P on passing current. If it is cut into halves and joined in parallel, it will consume power
a)
P
b)
P/2
c)
2P
d)
4P
|
|
Pooja Shah answered |
Original power consumed, P = V2/R
When used in parallel
RP = R/4
∴ New power consumed when two halves in parallel
When used in parallel
RP = R/4
∴ New power consumed when two halves in parallel
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 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.
Light from an object enters the eye through the pupil and travels to the back of the eye, forming an image on the retina. What is the orientation of the retinal image, as compared to that of the original object?- a)Turned to the left
- b)Upside down
- c)Same direction
- d)Turned to the right
Correct answer is option 'B'. Can you explain this answer?
Light from an object enters the eye through the pupil and travels to the back of the eye, forming an image on the retina. What is the orientation of the retinal image, as compared to that of the original object?
a)
Turned to the left
b)
Upside down
c)
Same direction
d)
Turned to the right
|
|
Diana Nair answered |
The image formed on the retina is Real and Inverted (Upside down) image.But we see all objects virtual and erect this is because the image formed on the retina is carried to the brain as electrical signals by the optical nerves.In the brain the brain flips the image formed so that we can see the image as an erect image.
When white light enters a prism, it gets split into its constituent colours. This is due to- a)different refractive index for different wavelength of each colour
- b)each colours has same velocity in the prism
- c)prism material have high density
- d)Scattering of light
Correct answer is option 'A'. Can you explain this answer?
When white light enters a prism, it gets split into its constituent colours. This is due to
a)
different refractive index for different wavelength of each colour
b)
each colours has same velocity in the prism
c)
prism material have high density
d)
Scattering of light
|
|
Gaurav Kumar answered |
Dispersion takes place because refractive index of the material of prisra is different for different wavelength.
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.
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
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