Explore topic-wise InterviewSolutions in .

This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

3851.

What is the cause of random wavering or flickering of the objects near a fire or on a very hot day ?

Answer»

Solution :AIR above the fire is hot. The hotter air is less DENSER than the colder air. This difference in density leads to difference in refractive indices and causes refraction. This RESULTS in changes in the APPARENT image of the object.
Discussion
3852.

Define Angle of friction and Angle of repose .Show that angle of friction is equal to angle of repose for a rough inclined plane. A block of mass 4 kg resting on a rough horizontal force of 30 N is applied on .If g=10m//s^(2). Find the total contactforce exerted by the plane on the block .

Answer»

Solution :Angle of friction : The angle made by the resultant of the Normal reaction and the limiting with Normal reaction is called angle of friction `(phi)`
Angle of repose : Let a body of mass m is placed on a rough inclined plane . Let the angle with the horizontal `'theta'` is gradually increased then for a particular angle of INCLINATION (say`alpha` ) the body will just slide down without acceleration . This angle`theta=alpha` is called angle of repose . At this stage the forces acting on the body are in EQUILIBRIUM.
Equation for angle of repose :
Force acting on the body in vertically downward direction - W - MG .
By resolving this force into two compnents .
(1)Force acting along the inclined plane in downward direction - mg `sintheta` .
This component is resposible for downward motion .
(2) The component mg `costheta` , which is balaneced by normal reaction .

If the body slides down without acceleration resultant force the body is zero , then
mg`sin theta` = Frictional force `(f_(k))`
mg `costheta` = Normal reaction (N.R)
But coefficient friction
`mu_(k)=(f_(k))/(N.R)=(mgsintheta)/(mgcostheta)=tantheta`
`thereforemu_(k)=tanalpha`
Hence tangent of angle of angle of repose`(tan theta)` is EQUAL to COEFFIECIENT of friction `(f_(k))`between the bodies .
(b ) When the block rests on the horizontal surface , it is in equilibrium under the action of four forces . They are
(i)Normal reaction (N)
(ii) Weight of the block (mg)
(iii) Horizontal force (30N)
Limiting frictional force`(f_(L))`

If the applied horizontal force is equal to the limiting frictional force , then only the block will be ready to move on the rough horizontal surface i. e , `f_(L)` = horizontal force applied .
`therefore`Total contact force = 30 N .
Discussion
3853.

A heater is marked 1000 W. The energy consumed by it in ten hours is

Answer»

10J
10 KJ
10 KWH
100 KJ

SOLUTION : 10 kWh
Discussion
3854.

What kind of energy transformation takes place in an electric motor ? Name any two devices which useelectric motor as an essential component of theirworking .

Answer»

Solution :In an ELECTRIC motor, electrical ENERGY is converted into mechanical energy. Electric motor is used as an essentialcomponentin electric fan, WASHING machine, ETC.
Discussion
3855.

(i) List any five properties of light (ii) State Rayleigh' law of scattering.

Answer»

Solution :(a) Light is a from of energy .
(B) Light always travel along a straight LINE.
(c) Light does not need any medium for its propagation . It can even travel through VACUUM.
(d) The seed of light in vacuum or air is `C =3 xx10^(8)"ms"^(-)`
(E) Different coloured light has different wavelength and FREQUENCY.
(ii) Rayleigh.s scattering law sates that .. The amount of scattering of light is inversely proportional to the fourth power of its wavelength.. .
Amount of scattering `S prop 1/lamda^4`
Discussion
3856.

Find out, from Table 10.3, the medium having highest optical density. Also find the medium with lowest optical density.

Answer»

Solution :HIGHEST OPTICAL density : 2.42 (DIAMOND)
Lowest optical density : 1.0003(AIR)
Discussion
3857.

Four student have made the following circuit diagrams for determining the equivalent resistance of two resistors connected in series : The correct circuit diagram is :

Answer»

A
B
C
D

Solution :NA
Discussion
3858.

Lets Think. If frog population declines all of a sudden : What will be overall effect on that ecosystem ?

Answer»

Solution :The increasing number of grasshoppers will destroy all the PADDY crops. Also, the number of TERTIARY consumers LIKE snakes willdecrease due to LACK of FOOD.
Eventually, this will disturb the entire food chain and will cause imbalance in the ecosystem.
Discussion
3859.

There is a stick half of which is wooden and half is of steel. (i) it is pivoted at the wooden end and a force is applied at the steel end at right angle to its length (ii) it is pivoted at the steel end and the same force is applied at the wooden end. In which case is the angular acceleration more and why ?

Answer»

Solution :I (first case) `GT` I(SECOND case)
`therefore TAU = I ALPHA`
`rArr alpha` (first case) `LT alpha` (second case)
Discussion
3860.

Dinesh is a student of 10th standard. He went to a remote area of Rajasthan for trekking with his friends. Dinesh found that it was a sparsely inhabited area. He was surprised to know that there was still no electricity in this area. The children also had to study with kerosene lamps at night. The village farmers used diesel to run irrigation pumps. Actually, there were no power transmission lines which could bring electricity to this remote area. Dinesh was really disturbed by the living conditions of the people in this part of Rajasthan. One day Dinesh gathered all the people of village in the village school. He told them that if they put pressure on their area MLAs and MP for making available the required funds, then he could tell them about the devices to light up their homes and streets at night, play radio and television and also run irrigation pumps with electricity without there being power transmission lines. All the people agreed and Dinesh described them the devices to get electricity in their area in detail. The village people were very happy to know this and soon they got electricity in their area. (a) What was the device described by Dinesh to the village people to obtain electricity locally ? (b) What source of energy is made use of in this device to obtain electricity ? (c) Why do you think this device is more appropriate for an area like Rajasthan ? (d) What is the name of the single unit of this device ? What values are shown by Dinesh in this incident ?

Answer»

Solution :(a) Solar panels.
(b) Solar energy (Sun's energy or SUNLIGHT energy).
(c) Because Rajasthan GETS a LOT of sunshine throughout the year.
(d) Solar cell.
(e) The values shown by Dinesh in this incident are (i) General awareness (knowledge) about the alternative SOURCES of energy (here solar energy) (ii) Concern for the ENVIRONMENT to improve it (by reducing air pollution), and (iii) Desire to help people improve their life (by providing electricity).
Discussion
3861.

Proboscis : Hemichordata : : Suctorial mouth : ……

Answer»

SOLUTION :CYCLOSTOMATA
Discussion
3862.

In which condition a body lying in gravitational field is in stable equilibrium ?

Answer»

SOLUTION :When VERTICAL line through centre of gravity passes through the BASE of the body.
Discussion
3863.

A body is suspended on a spring balance in a ship sailing along the equator with a speed v'. If omega is the angular speed of the earth and omega_(0) is the scale reading when the ship is at rest, the scale reading when the ship is sailing is

Answer»

`w_(0)`
zero
`W_(0)(1 pm (2wv)/(G))`
`W_(0)(1- (g)/(2w))`

Answer :C
Discussion
3864.

Define inertia. Give its classification .

Answer»

SOLUTION :The inherent property of the body to resist any CHANGE in its state of rest or the state of uniform motion unless it is influenced UPON by an external unbalanced FORCE is known as " inertia " .
CLASSIFICATION :
(i) Inertia of rest
(ii) Inertia of motion
(iii) Inertiaof direction .
Discussion
3865.

Draw schemastic representastion of power plant based on natural gas and answer the following questions: a. At which place is natural gas power plant sitatued in Maharashtra? b. How is pollution reduced in natural gas based power plant? c. Give two examples of eco -friedly electricity process.

Answer»

SOLUTION :
Schematic representation of power plant based on natural gas.
a. Natural gas power plant is situated at Anjanvelin MAHARASTRA.
b. Natural gas does not contain sulphur and hence its burning does not cause pollution. Using such power THEREFORE reduced pollution.
c. Eco-friendly ELECTRICITY process: Wind energy and solar energy are eco-friendly processes.
Discussion
3866.

A force exerted on abody of mass 100 g changes its speed by "0.2 ms"^(-1) in each second. Calculate the magnitude of the force.

Answer»

SOLUTION :GIVEN, MASS `m=100g=0.1kg` and ACCELERATION `a=200cms^(-2)=0.2ms^(-2)`.
`F=ma`
`=0.1xx0.2`
`F=0.02N`
Discussion
3867.

The power of …………….. Is negative and ……………… is positive.

Answer»


ANSWER :CONCAVE LENS, CONVEX lens
Discussion
3868.

The resistance of an electric bulb drawing 12A current at 6.0V will be:

Answer»

`0.5 Omega`
`5 Omega`
`0.2 Omega`
`2 Omega`

Solution :RESISTANCE of BULB `R=V/I=(6.0 V)/(1.2A)=5.0 Omega`
Discussion
3869.

How is the strenght of the magnetic fieldat a point near a wirerelated to thestrenght of the electriccurrentflowingin the wire ?

Answer»

SOLUTION :Strenght of MAGNETICFIELDIS directly PROPORTIONAL to the strenghtof current .
Discussion
3870.

Tell me who am I ? What is my class/phylum ? I am sedenatary marine animal drinking water all the time through numerous pores on the body .

Answer»

SOLUTION :SPONGE , PHYLUM : PORIFERA.
Discussion
3871.

To projectthe rocketswhich of the following principle(s) is /(are) required ?

Answer»

Newton's THRID law of MOTION
Newton's lawof GRAVITATION
Law opf CONSERVATION of linear momentum
Both (a) and (c)

SOLUTION :Both (a) and (c)
Discussion
3872.

Class II levers are designed to have :

Answer»

`M.A.=V.R.`
`M.A.gtV.R.`
`M.A. GT 1`
`M.A. LT 1`

ANSWER :C
Discussion
3873.

Expresss Joule's law of heating mathematically. What is the resistance of 12m wire having radius 2 times 10^-4m and resistivity 3.14 times 10^-8 Omega .m?

Answer»

Solution :For mathematical expression of Joule.s law of heating, see point Number 29 under the heading " Chapter At a GLANCE"
As PER Question length of WIRE L=12m, radius `r=2 TIMES 10^-4 m` and resistivity `p=3.14 times 10^-8 Omega .m`
`THEREFORE` Resistance of given wire `R=(rho L)/A=(rho L)/(pi r^2)= (3.14 times 10^-8 times 12)/(3.14 times (2 times 10^-4)^2)=3 Omega`
Discussion
3874.

Why do we see a rainbow in the ske only after rainfall ?

Answer»

Solution :Raindrops present in atmpsphere after rainfall act as tiny PRISMS and REFRACT, dispere, and internally relfect the incident sunlight. This COMBINED effect leads to the formation of RAINBOW in the sky after rainfall.
Discussion
3875.

Most harmful effect of environmental pollution occurs on the living organisms. Have you seen some examples of this in your area ?

Answer»

Solution :i. Air pollution `:`
SMOG can result in a number of respiratory health effects. Also,acid RAIN can be harmful to plants as WELL as aquatic life.
ii. Water pollution `:`
Organic pollutants in water bodies can cause algal BLOOMS, mass mortality of fishes and europhication.
Discussion
3876.

In an experiment to find the equivalent resistance of two resistors connected in series, a student uses the circuit shown : This circuit will give :

Answer»

correct READING for VOLTAGE V but INCORRECT reading for current I
correct reading for current I but incorrect reading for voltage (V)
correct readings for both voltage V and current I
Incorrect readings for both current I and voltage V

Solution :NA
Discussion
3877.

List anytwo industries based on forest produce.

Answer»

SOLUTION :Paper , timber , lac , SPORTS equipments. (Any TWN)
Discussion
3878.

Destroying trees is to destroy everything. Support this statement with examples

Answer»

Solution :(1) When a single huge tree is felled many living organisms which are dependent on it, are exterminated. (2) Many insects, FUNGI, birds, etc. lose their habitat. (3) Trees take upcarbon dioxide from theatmosphere and release oxygen. These natural are also hindered dut to loss of trees. (4) Due to trees there is shade, cooler atmosphere and increase in the rainfall. When such trees are destroyed all the components in the ecosystem are destroyed too.
Discussion
3879.

Halogen in the period 3.

Answer»

SOLUTION :CHLORINE
Discussion
3880.

Observe the diagram given and aswer the question asked. a. Identify the parts labeled A,B,C,D,E.

Answer»

Solution :A `RARR` IRIS, B `rarr` Pupil, ( C)`rarr` Crystalline LENS
D `rarr` CORNEA E `rarr` Retina
Discussion
3881.

Body organization of human has been shown in the following figure. Use appropriate labels for different organs present in human body .

Answer»

SOLUTION :
There are different organs in the human body . The liver , pancreas , stomach , intestine , etc. related to the digestive system and a pair of kidney concerned with excreation is present in the abdominal cavity . The cranial cavity shows BRAIN and sense organs . In the THORACIC cavity there are LUNGS and heart . In addition to these organs , there are network of blood capillaries , nerve network , etc. which is spread from head to TOES.
Discussion
3882.

Draw a neat diagram showing fertilization in a flower and label (a) Pollen tube, (b) male germ cell and (c ) female germ cell, on it. Explain the process of fertilization in flower what happens to the (i) ovary and ovule after fertilisation ?

Answer»

Solution :
Process of fertilization : 1. On reaching the stigma, pollen grain germinates carrying the two male gametes in pollen tube.
2. The first male gamete fuses with the egg cell, present in the embryo sac resulting in formation of ZYGOTE.
3. The second male gamete fuses with secondary nucleus and result in formation of primary endosperm nucleus this is known as double fertilisation.
4.After fertilisation, the ovule develops and CONVERTS into a seed containing embryo the embryo is the future plant and when it is provided with suitable conditions like water air and optimum temperature, it develops into a seedling.
(i)The ovary grows rapidly and RIPENS to form a fruit the fruit and CLOSES the seeds the seed contains embryo which has a plumule and a radicle. radicle give rise to root and plumule gives rise to shoot.
(ii) Ovule forms the embryonal axis inside the seed.
Discussion
3883.

You are walking by a store along with your friend. Both of you see a poster on the wall saying 'Say No To Plastics'. Your friend disagrees with the content of the poster and recounts the uses and advantages of plastic. You contradict him saying that plastics are harmful to the environment. Answer the following questions based on the above information: (i) Which values are being disrespected by your friend by not agreeing with you? (ii) How will you convince him that plastics are harmful to the environment? (iii) Government has banned the use of plastics and has asked to use paper bags or jute bags instead. How will you get the decision implemented effectively?

Answer»

Solution :(i) Environmental protection, reducing environmental pollution, concern for life.
(ii) Plastics are non-biodegradable. If they are EATEN by animals they block their digestive system and if they get buried in soil it would become INFERTILE.
(iii) (a) Totally avoid using plastics though personal action.
(B) ORGANISE mass campaigns with the help of friends and family MEMBERS.
Discussion
3884.

A person can see distant objects clearly but nearby objects appear blurry. Which defect is he suffering from ?

Answer»

SOLUTION :HYPERMETROPIA or far-sightedness.
Discussion
3885.

Do hard surfaces reflect sound better than soft ones?

Answer»

Solution :Generally, hard surfaces reflect SOUND BETTER than soft surfaces. But sound reflects quite well from rough surfaces than polished surfaces.
Discussion
3886.

Two masses of 5 kg and 3 kg are suspended with help of mass less inextensible string as shown. Calculate T_1 and T_2 when system is going upwards with acceleration m//s^2. ("Use g"= 9.8m//s^2).

Answer»

SOLUTION :According Newton’s second LAW of motion
(i) `T_(1)-(m_(1)+m_(2))g=(m_(1)+m_(2))a`
`T_(1)=(m_(1)+m_(2))(a+g)`
=(5+3) (2+9.8)
`T_(1)=94.4N`
(ii) `T_(2)-m_(2)g=m_(2)a`
`T_(2)=m_(2)(a+g)`
`T_(2_)=3(2+9.8)`
`T_(2)=35.4N`
Discussion
3887.

An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of image.

Answer»

SOLUTION :u=-10cm, f=15cm,v=?
`1/v=1/f-1/u=1/15-1/(-10)=1/15+1/10=25/150`
`v=150/25=6cm`
IMAGE is virtual erect, SMALL in size and BEHIND the MIRROR.
Discussion
3888.

While doing an experiment for the determination of focal length of a convex lens, Raja Suddenly dropped the lens. It got broken into two halves along the axis. If he continues his experiment with the same lens, Is thereany change in the focal length ?

Answer»

Solution :No, there is no change in the focal length of the CONVEX lens EVEN if it is broken into two halves . Only the intensity of the image OBTAINED will be less.
Discussion
3889.

A source of sound is moving with a velocity of 50ms^(-1) towards a stationary listener. The listener measures the frequency of the source as 1000Hz. What will be the apparent frequency of the source when it is moving away from the listener after crossing him? (velocity of sound in the medium is 330ms^(-1)).

Answer»

Solution :When the source is MOVING TOWARDS the STATIONARY listener, the expression for APPARENT frequency is
`n.=((v)/(v-v_(s)))n`
`1000=((330)/(330-50))n`
`n=((1000xx280)/(330))`
`n=848.48Hz`
The actual frequency of the sound is 848.48 Hz. When the source is moving away from the stationary listener, the expression for apparent frequency is
`n.=((v)/(v-v_(s)))n`
`=((30)/(330+50))xx848.48`
=736.84Hz`
Discussion
3890.

While doing an experiment for the determination of focal length of a convex lens, Raja Suddenly dropped the lens. It got broken into two halves along the axis. If he continues his experiment with the same lens,can he get the image ?

Answer»

SOLUTION :YES , he can GET the IMAGE of same SIZE.
Discussion
3891.

Where does this energy go ?

Answer»

SOLUTION :The ENERGY is TRANSFERRED from one object to another.
Discussion
3892.

Name (i) the light sensitive screen and (ii) diaphragm of the human eye.

Answer»

SOLUTION :(i) RETINA. (II) IRIS
Discussion
3893.

Peep hole in door, magnifying glass, camera, telescope.

Answer»

Solution :PEEP hole in DOOR. Door peep hole uses CONCAVE lens while other devices make use of CONVEX LENSES.
Discussion
3894.

State the relation between the joule and the kilocalorie.

Answer»

Solution :The AMOUNT of heat necessary to raise the TEMPERATURE of 1 kg of water by `1^(@)C` from `14.5^(@)`C to `15.5^(@)C ` is CALLED one KILOCALORIE.
Discussion
3895.

Is it possible for a convex lens kept in one medium to act like a diverging lens when placed in medium ? Given reason.

Answer»

SOLUTION :Yes, it is possible. The medium surrounding the convex LENS should have a greater REFRACTIVE index when compared to the refractive index of the MATERIAL for the convex lens. In other WORDS, the surrounding medium should be denser than the material of the lens.
Discussion
3896.

What is the main advantage of having two eyes in front of the head ?

Answer»

Solution :It provides steropsis - a sense of DEPTH which HELPS to gauge DISTANCE of the OBJECTS clearly.
Discussion
3897.

A ray of light of wavelength 5400 Å suffers refractive from air to glass. Taking ""_(a)mu_(g)=3//2, find the wavelength of light in glass.

Answer»


ANSWER :3600 Å
Discussion
3898.

A point charge +q, is placed at a distance d from an isolated conducting plane. The field at a point P on the other side of the plane is

Answer»

directed PERPENDICULAR to the plane and AWAY from the plane
directed perpendicular to the plane but towards the plane
directed RADIALLY away from the POINT charge
directed radially towards the point charge

Answer :A
Discussion
3899.

Assertion: Control rods are known as 'neutron seeking rods'. Reason: Control rods are used to perform substained nuclear fission reaction.

Answer»

if both the assertion and the reason are true and the reason is the correct explanation of the assertion
If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion
Assertion is true, but the reason is false
Assertion is also, but the reason is true

Solution :CONTROL rods are used to control the number of neutrons in order to have SUSTAINED chain REACTION. They absorb the neutrons. (they SEEKING th NEUT)
Discussion
3900.

A pump is used to lift 500 kg of water from a depth of 80 m in 10 s .Calculate : (a)the work done by the pump . (b)the power at which the pump works,and (c )the power rating of the pump if its efficiency is 40% (Take g =10 m s^(-2)) [Hint :Efficiency=("use power")/("power input")]

Answer»

Solution :(a) `4xx10^(5)J` (B)40 KW (c )100 kW
Discussion