885 + Interview Questions in Physics in Class 8 Page 16 InterviewSolution

751.	In the single touch method of magnetization , the north pole of a bar magnet is rubbed against a steel rod. Then the polarity of the end of the steel rod at which the magnet leaves
Answer» is the SOUTH . is the north. depends UPON the material. none of these Answer :A

Discussion

752.	If 500 sound waves are produced in one minute, then find the time taken by a vibrating particle to move from its mean position to the immediate rarefactions
Answer» SOLUTION :(i) Half the time PERIOD (ii) 60 MS

Discussion

753.	The observation made of Faraday from the experiments on electromagnetic induction is (are) that ________. (A) the deflection in the galvanometer increases when a strong magnet is used (B) the induced current in the coil is alternating in nature
Answer» Only A is true Only B is true Both A and B are true Both A and B are false Answer :C

Discussion

754.	Which of the following cannot be charged easily by friction?
Answer» A PLASTIC scale A COPPER rod An inflated balloon A woolen cloth Answer :A::C::D

Discussion

755.	When the whole sheet of paper is spread on the table, it represents one plane.The incident ray, the normal at the point of incidence and the reflected ray are all in this pIane. When you bend the paper you create a plane different from the plane in which the incident ray and the normal lie. Then you do not seethe reflected ray.What does it indicate?
Answer» Answer :It INDICATES that the INCIDENT RAY,the NORMAL at the POINT of incidence and the reflected ray all lie in the same plane.

Discussion

756.	An owl has a mass of 3 kg. It dives to catch a mouse on the ground losing 900 J of potential energy. How high was the bird to begin with?
Answer» SOLUTION :m=3 KG , PE=900 J , `g=10 m//s^2` PE=mgh So H =PE/mg `=900/3xx10=900/30=90/3`m = 3 m

Discussion

757.	One of the limbs of a mercury manometer is connected to a gas cylinder. The mercury level in the limb connected to the gas cylinder is 10 cm higher than that in the other limb. Then the gauge pressure of the gas is ____ cm of Hg.
Answer» SOLUTION :N//A

Discussion

758.	The kinetic energy of a car is calculated to be 1250000 J. If the car has a mass of 1000 kg, with what speed is it moving?
Answer» Solution :KE=1250 kJ , m=1000 kg USING the formula`KE=1/2mv^2` we GET : `V=(2 KE//m)^(1//2)` `v=(2xx1250000//1000)^(1//2)=(2500)^(1//2)` v=50 m/s

Discussion

759.	State whether the following statements are true or false: Deflection in the magnetic compass indicates that current is passing.
Answer» ANSWER :1

Discussion

760.	Identify the wrong statement. The momentum of a body is
Answer» the PRODUCT of mass and velocity of the body the product of force and time the VECTOR quantity measured in KG m `s^(-1)` in S.I. system. Answer :B

Discussion

761.	Why do you sprinkle fine powder on the carrom board?
Answer» ANSWER :We sprinkle FINE POWDER on the carrom BOARD to reduce friction and increase efficiency.

Discussion

762.	Consider a liquid contained in a vessel. The liquid solid adhesive force is very weak as compared to the cohesive force in the liquid. The shape of the liquid surface near the solid shall be
Answer» equal to LESS than greater than less than or equal to Solution :A convex meniscus is formed when the COHESIVE FORCE greater than the adhesive.

Discussion

763.	Do you recall what happens to the air in the bicycle tube when it has a puncture? Do these observations suggest that air excerts p-ressure on the inner walls of an inflated balloon or a tube?
Answer» Answer :When a bicycle TUBE has a puncture, the AIR in it ESCAPES LEAVING it DEFLATED.

Discussion

764.	Choose the correct option(Multiple choice questions): ____ is used in electroplating of iron.
Answer» COPPER Chromium Zinc Tin Answer :C

Discussion

765.	A vernier calipers has 25 divisions on the vernier scale, An object is held between the external jaw of this instrument. If the zeroth division of the vernier scale is to the left 32nd division of the main scale and the 20th division of the vernier scale coincides with a main scale division, determine the measurement of the object. (Take 1 M.S.D. = 0.5 mm )
Answer» SOLUTION :Length or diameter = [ DIFFERENCE of the OBSERVED READING on the TWO jaws with the object held] -[difference of the observed reading when the jaws are closed]. (ii) M.S.R = 10.2 cm V.C.D. = 6

Discussion

766.	Fill in the blanks : We see moving picture in movies because a number of separate pictures are moved across the eye at the rate of________ pictures per second.
Answer» ANSWER :24

Discussion

767.	Greater the ____of the surface,greater will be the force of friction.
Answer» smoothness roughness shrapness both (B) and © Answer :A

Discussion

768.	If an object oscillates 30 times per second then, its frequency will be __________.
Answer» 30 0.033 300 `1/3` ANSWER :A

Discussion

769.	In above problem, if the police man is behind the thief and the initial distacen between them is 10 m, how much time will it take of thepolicmane to catch the thief?
Answer» Solution : Let the distacne travelled by the THIEF by d, when the polceman catches him. The distace travelled by the policeman `=(0.1d)` km= (100). Let the time TAKEN be t `:.2=(d)/(t)` `d=2t` `d=(d+0.1)/(t)` `5=(2t+0.1)/(t)` `5t=2t+0.13t=0.1` `t=(0.1)/(3)H` `h=0.1xx60` MINUTES `0.1xx20` minutes =2 mintues

Discussion

770.	Fill in the blanks : A ______ appears generally as a bright head with a long tail.
Answer» ANSWER :COMET

Discussion

771.	For greater stability, the position of center of gravity should be low and base area should be ______.
Answer» ANSWER :LARGE

Discussion

772.	State whether the following statements are true or false : The density of Saturn is less than that of water.
Answer» ANSWER :1

Discussion

773.	Name a disease caused due to deficiency of vitamin A in food.
Answer» Answer :NIGHT blindness is a DISEASE CAUSED DUE to deficiency of VITAMIN A in food.

Discussion

774.	Have you not seen a moving ball on the ground stopping after sometime?
Answer» Answer :Yes, a moving ball on the GROUND stops after sometime if no external FORCE is APPLIED.

Discussion

775.	A car A has just overtaken car B which is moving in the same direction as A. Gien below are few cases explanainig the motion of the cars at that instance. Identify th givencases as cases that are necessarily true, cases that can be true only under certain conditions and cases that are necessarily false. (i) The car is accelerating and car B isb decleariting (ii) The car A is decelearting and car B accelerating (iii) Both car accelerating (iv) Both cars are decelerating (v) Both cars moving with uniform velocity (vi) Car A is moving withuniform velocity and car B is accelerationg. (vii) Instantaneous spee of car A is less than that of car B (viii) Instaneous speed of car B is less thatn that of car A.
Answer» Solution :What is instantaneous velocity? When car A just overtaken car B, which ONE has higher insaneous velocity? If the instaneous velocity of A is GREATER than that of B, then is it a must that it should be accelerated or DECELERATED? Is it not possible that both the cars have acceleration or deceleration or more with UNIFORM velocity?

Discussion

776.	Respiratory disorders are caused when the capacity of R.B.C, to carry oxygen is lessened. This happens when ________is inhaled.
Answer» SULPHUR dioxide nitrogen trioxide carbon dioxide carbon monoxide Answer :D

Discussion

777.	Both the galvanometer and galvanoscope can be used to________.
Answer» MEASURE A.C. voltage measure current measure D.C. voltage detect SMALL currents Answer :D

Discussion

778.	Fill in the blanks : An object can acquire charge when it is _______ with another object.
Answer» ANSWER :RUBBED

Discussion

779.	When bulbs are connected in series, same current flows through them.
Answer» ANSWER :1

Discussion

780.	Among the given fuels, justify which one is a good fuel ?
Answer» SOLUTION :CHARACTERISTICS of a GOOD FUEL.

Discussion

781.	The string of a sitar also gives out a musical sound. But, if a musical sound becomes too loud, would it remain melodious?
Answer» Answer :No, if a musical sound becomes too loud, it WOULD not REMAIN MELODIOUS.

Discussion

782.	Can we make another tester which can detect a weak current?
Answer» ANSWER :We can use LED to DETECT a weak current as LED glows EVEN when SMALL electric current is passed through it.

Discussion

783.	Match the entries in column A with the appropriate ones in Column B
Answer» Answer :A: G B: IC:FD:AE:hF:j G:EH:b I:c J:d

Discussion

784.	In the phenomenon of electromagnetic induction, __________energy of the coil or magnet is converted to _________energy.
Answer» MAGNETIC, ELECTRIC electric, magnetic electric, kinetic kinetic, electric ANSWER :D

Discussion

785.	An unmagnetized steel bar buried in earth in the north -south direction would, after a few days, exhibit magnetic properties, making it a weak magnet. Explain by giving reasons how this is possible. In what way will the effect be different if the steel bar is to be placed above the surface of earth ?
Answer» Solution :What happens to an iron BAR placed NEAR a strong magnet ? COMPARE an iron bar placed in a strong magnetic field with an iron bar placed INA weakmagnetic field.

Discussion

786.	Which is the next nearest star from the Earth after the Sun?
Answer» ANSWER :Alpha Centauri is the next NEAREST STAR from the Earth after the SUN.

Discussion

787.	If the relative density of a solid is less than one, then
Answer» it sinks in water. it floats in water. it sinks in all the liquids it floats in all the liquids Solution :If relative DENSITY of a SOLID is LESS than ONE, it floats in water.

Discussion

788.	A wind energy farm converts _______.
Answer» SOLAR ENERGY to WIND energy wind energy to ELECTRIC energy electrical energy to wind energy wind energy to solar energy Answer :B

Discussion

789.	Fill in the blanks : Friction acts on the ______ of the object
Answer» ANSWER :SURFACE

Discussion

790.	The density of ice is 901 kg m^(-3). What percentage of ice lies below water ? The density of sea water is 1011 kg m^(-3). What fraction of an iceberg can be seen by us if the ice berg has the same density as that of ice ?
Answer» Solution :(i) Apply the LAW of floatation. Weight of the FLOATING body = weight of the displaced liquid. This implies, V.D. =vd The PERCENTAGE of the ice lying celow the water is `=(v)/(V)xx100` Apply the same concept for the iceberg floating in sea water. The percentage of the iceberg lying above the sea water is `=(100-(v)/(V)xx100)` (II) 0.11

Discussion

791.	Glass does not allow _______________ to flow through it.
Answer» ANSWER :ELECTRIC CHARGE

Discussion

792.	Clouds get electrically charged when
Answer» the ultraviolet rays of sun falls on them. air MOLECULES rub against water molecules. cold CURRENTS of air rub against HOT currents of air. Both (b) and (C) Answer :D

Discussion

793.	Mark the following statements as true (T) or false (F) . Uranus is the farthest planet in the Solar System.
Answer» ANSWER :F

Discussion

794.	Fill in the blanks: We should not experiment with the electric supply from ___ or a ___ or an ___.
Answer» ANSWER :MAINS, GENERATOR, INVERTER

Discussion

795.	What do you mean by time period?
Answer» Answer : The time taken by a BODY or an OBJECT to COMPLETE one oscillation is CALLED time PERIOD.

Discussion

796.	State whether the following statements are true or false : The Pole star is not visible from the southern hemisphere.
Answer» ANSWER :1

Discussion

797.	The degree of hotness or coldness of a body is called its
Answer» HEAT capacity Temperature Latent heat capacity None of these Answer :B

Discussion

798.	Take a long thread. Place your hands over your ears and get someone to place this thread round your head and hands. Ask her to make the thread taut and hold its ends in - one hand. Now ask her to draw her finger and thumb tightly along the thread. Can you hear a rolling sound like that of a thunder? Now repeat the activity while another friend stands near both of you. Can he hear any sound?
Answer» ANSWER :Yes, we can HEAR a ROLLING sound LIKE that of a thunder. No, the FRIEND standing near both of us cannot hear any sound.

Discussion

799.	Describe with the help of a diagram an instrument which can b e used detect a charged body.
Answer» Answer :An instrument used to detect a CHARGED body is called an electroscope. It can be constructed easily with the HELP of a jar, a cardboard, a metal rod or a metal paper CLIP and TWO strips of ALUMINIUM body.

Discussion

800.	When does a charged body get discharged?
Answer» Answer :A CHARGED body gets DISCHARGED when it COMES into contact with our body and loses its CHARGE to the earth through our body.

Discussion

Explore topic-wise InterviewSolutions in .

In the single touch method of magnetization , the north pole of a bar magnet is rubbed against a steel rod. Then the polarity of the end of the steel rod at which the magnet leaves

If 500 sound waves are produced in one minute, then find the time taken by a vibrating particle to move from its mean position to the immediate rarefactions

The observation made of Faraday from the experiments on electromagnetic induction is (are) that ________. (A) the deflection in the galvanometer increases when a strong magnet is used (B) the induced current in the coil is alternating in nature

Which of the following cannot be charged easily by friction?

An owl has a mass of 3 kg. It dives to catch a mouse on the ground losing 900 J of potential energy. How high was the bird to begin with?

One of the limbs of a mercury manometer is connected to a gas cylinder. The mercury level in the limb connected to the gas cylinder is 10 cm higher than that in the other limb. Then the gauge pressure of the gas is ____ cm of Hg.

The kinetic energy of a car is calculated to be 1250000 J. If the car has a mass of 1000 kg, with what speed is it moving?

State whether the following statements are true or false: Deflection in the magnetic compass indicates that current is passing.

Identify the wrong statement. The momentum of a body is

Why do you sprinkle fine powder on the carrom board?

Consider a liquid contained in a vessel. The liquid solid adhesive force is very weak as compared to the cohesive force in the liquid. The shape of the liquid surface near the solid shall be

Do you recall what happens to the air in the bicycle tube when it has a puncture? Do these observations suggest that air excerts p-ressure on the inner walls of an inflated balloon or a tube?

Choose the correct option(Multiple choice questions): ____ is used in electroplating of iron.

Fill in the blanks : We see moving picture in movies because a number of separate pictures are moved across the eye at the rate of________ pictures per second.

Greater the ____of the surface,greater will be the force of friction.

If an object oscillates 30 times per second then, its frequency will be __________.

In above problem, if the police man is behind the thief and the initial distacen between them is 10 m, how much time will it take of thepolicmane to catch the thief?

Fill in the blanks : A ______ appears generally as a bright head with a long tail.

For greater stability, the position of center of gravity should be low and base area should be ______.

State whether the following statements are true or false : The density of Saturn is less than that of water.

Name a disease caused due to deficiency of vitamin A in food.

Have you not seen a moving ball on the ground stopping after sometime?

Respiratory disorders are caused when the capacity of R.B.C, to carry oxygen is lessened. This happens when ________is inhaled.

Both the galvanometer and galvanoscope can be used to________.

Fill in the blanks : An object can acquire charge when it is _______ with another object.

When bulbs are connected in series, same current flows through them.

Among the given fuels, justify which one is a good fuel ?

The string of a sitar also gives out a musical sound. But, if a musical sound becomes too loud, would it remain melodious?

Can we make another tester which can detect a weak current?

Match the entries in column A with the appropriate ones in Column B

In the phenomenon of electromagnetic induction, __________energy of the coil or magnet is converted to _________energy.

Which is the next nearest star from the Earth after the Sun?

If the relative density of a solid is less than one, then

A wind energy farm converts _______.

Fill in the blanks : Friction acts on the ______ of the object

The density of ice is 901 kg m^(-3). What percentage of ice lies below water ? The density of sea water is 1011 kg m^(-3). What fraction of an iceberg can be seen by us if the ice berg has the same density as that of ice ?

Glass does not allow _______________ to flow through it.

Clouds get electrically charged when

Mark the following statements as true (T) or false (F) . Uranus is the farthest planet in the Solar System.

Fill in the blanks: We should not experiment with the electric supply from ___ or a ___ or an ___.

What do you mean by time period?

State whether the following statements are true or false : The Pole star is not visible from the southern hemisphere.

The degree of hotness or coldness of a body is called its

Describe with the help of a diagram an instrument which can b e used detect a charged body.

When does a charged body get discharged?

In the phenomenon of electromagnetic induction, __energy of the coil or magnet is converted to _energy.

Fill in the blanks: We should not experiment with the electric supply from _ or a _ or an ___.