885 + Interview Questions in Physics in Class 8 Page 17 InterviewSolution

801.	A block of weight 100 N and dimenions 50 cm x 30 cm x 10 cm rests on a table in three different positions with its base as (a) 50 cm x 30 cm, (b) 30 cm x 10 cm, (C) 50 cm x 10 cm. Calculate the pressure exerted in each case.
Answer» ANSWER :(a)666.67 PA , (B)3333.3 Pa, (C ) 2000 Pa

Discussion

802.	What is lightning conduction? How does it work?
Answer» Answer :LIGHTNING conductor is an used to protect buildings from lightning. Is is MADE of a tall METAL ROD, taller than the HEIGHT of the building.

Discussion

803.	Match the entries in Column A with the appropriate entries in Column B
Answer» Answer :`A : F "" B : i "" C : G "" D :a "" E:h "" F :e "" G:b "" H:J "" I:d "" J:c`

Discussion

804.	What is electrostatic force?
Answer» ANSWER :When an OBJECT is RUBBED with another object such as paper or cloth, it GETS CHARGED.

Discussion

805.	Can liquids conduct eIectricity?
Answer» ANSWER :YES,some LIQUIDS can CONDUCT ELECTRICITY.

Discussion

806.	In the electrical method of magnetization, the polarity of the end in which current flows in clockwise direction
Answer» is the NORTH POLE is the sourth pole does not DEPED upon the direction of currrent FLOW cannot be determined Solution :In the electrical method of magnetization, if the current flows in clockwise direction, then south pole is FORMED.

Discussion

807.	Which one of the following statements is true ?
Answer» WATER FORMS concave MENISCUS on account of high cohesive FORCES. Mercury forms concave meniscus on account of more adhesive force than the cohesive forces. Water forms convex meniscxus on account of high adhesive forces than the cohesive forces. Mercury forms convex meniscus on account of more cohesive force than adhesive force. Solution :N//A

Discussion

808.	A tuning fork is excited first in air and then in water. In which case is the amplitude more ? Explain.
Answer» Solution :AMONG air and WATER find which exerts more FRICTIONAL FORCE. How is the amplitude affected by the frictional force ?

Discussion

809.	Calculate the kinetic energy of a 20 kg wooden cart moving with a speed of 5 m/s. Calculate the kinetic energy again when the speed is doubled.
Answer» Solution :`KE=1/2mv^2`, m=20 kg , v=5 m/s `KE=1/2xx20xx(5)^2` =250 J When SPEED doubles , v=10 m/s Then , `KE=1/2 xx 20 xx 10 xx 10`= 1000 J

Discussion

810.	Fill in the blanks: Common salt when dissolved in distilled water makes it a good ___ of electricity.
Answer» ANSWER :CONDUCTOR

Discussion

811.	Arrange the following steps in proper sequence to determine the relative density of liquid by using a constant immersion hydrometer. (a) The test tube is made to float in the given liquid. (b) The weight of the test tube with lead shots in air is determined (W_(1)). ( c) The depth of the test tube immersed in water (h) is determined. (d) The test tube is made to float in water. (e ) Lead shots are added or removed from the test tube such that the test tube is immersed to the same depth (h) in the given liquid. (f) The relative density of the liquid is measured as (W_(1))/(W_(1)). (g) The test tube is taken out from the given liquid and its weight (W_(2)) is measured.
Answer» b d c a e g f b d c a e f g b g f e a c d b a d c e f g Solution :(a) The weight of the test TUBE with lead shots in air `(W_(1))` is measured. (b) The test tube is made to FLOAT in water. (c ) The DEPTH of the test tube immersed in water (h) is determined. (d) The test tube is made to float in the GIVEN liquid. (e ) Lead shots are added or REMOVED from the test tube so that the test tube is immersed to the same depth (h) in the given liquid. (f) The test tube is taken out from the liquid and its weight `(W_(2))` is measured. (g) The relative density of the liquid is measured as `(W_(2))/(W_(1))`.

Discussion

812.	What is voice box?
Answer» ANSWER :In humans, the upper end of the WINDPIPE which produces sound by vibrating vocal CHORDS is KNOWN as voice box.

Discussion

813.	How can a magnet be demagnetized ?
Answer» Solution :Alilgnment of the MOLECULAR magnet CHANGES when an alternate CURRENT is PASSED through it.

Discussion

814.	State whether the following statements are true or false : After the full moon day,the sunlit part visible from the Earth decreases in size everyday.
Answer» ANSWER :1

Discussion

815.	Can you explain now why shoulder bags are provided with broad straps and not thin strap? And, why the tools meant for cutting and piercing always have sharp edges?
Answer» Answer :SHOULDER bags are provided with BROAD straps and not thin straps because broad STRAP will REDUCE the pressure excerted by the LOAD in the bag.

Discussion

816.	Behind the pupil of the eye is a lens which is thicker in the centre. What kind of lens is thicker at the centre?
Answer» ANSWER :A CONVEX LENS is THICKER at the CENTRE.

Discussion

817.	Explain the working principle of hydraulic press using Pascal's law.
Answer» BOYLE's law Charle's law Archimedes' principle Pascal's law Solution :N//A

Discussion

818.	How do you come to know that a 'period' is over in your school?
Answer» ANSWER :We COME to know that a 'period' is over in our SCHOOL when we hear the SOUND of ringing bell.

Discussion

819.	Take a metre scale or a long metal rod and hold its one end to your ear. Ask your friend to gently scratch or tap at the other end of the scale. Can you hear the sound of scratching? Ask your friends around you if they were able to hear the same sound?
Answer» ANSWER :YES, we can hear the SOUND of scratching. No, my friends were not ABLE to hear the sound.

Discussion

820.	Since muscular force can be applied only when it is in contact with an object, it is also called a contact force. Are there other types of contact forces?
Answer» ANSWER :YES, APART from musular FORCE, force of friction is also a KIND of contact force.

Discussion

821.	What do you mean by hearing?
Answer» Answer :The EARDRUM senses the VIBRATION of SOUND and sends the signals to the BRAIN. This process is called HEARING.

Discussion

822.	The power of a solar panel depends on (A) the arrangment of the solar cells in it. (B) the extent of surface area of the solar cell.
Answer» only A is true Only B is true. Both A and B are true Both A and B are false. Answer :C

Discussion

823.	If the radius of curvature of a convex mirror is 30 cm, what would be its focal length?
Answer» ANSWER :15 CM

Discussion

824.	The distance betweent he LFP and UFP of a thermometer is 18 cm. the readint on the thermometer in Fahrenheit scale when the length of the mercury thread is 8 cm is____
Answer» `212^(@)F` `112^(@)F` `80^(@)F` `180^(@)F` Answer :B

Discussion

825.	What is the density of milk if 1 mL of milk has a mass of 1.03 g?
Answer» ANSWER :1.03 g/mL=1.03 `"g/cm"^3`

Discussion

826.	Fill in the blanks : The upper most layer of the earth is called______.
Answer» ANSWER :CRUST

Discussion

827.	the process of transferring charge from a charged object to the earth is called______.
Answer» lightning earthing charging rubbing Answer :B

Discussion

828.	Gases do not have rigidity. Select the reason from the following .
Answer» The cohesive FORCE is negligible The adhesive force is very HIGH The cohesive force is very high None of the above Solution :Cohesive force in gas is negligible because of this the MOLECULES in GASES are largely SEPARATED.

Discussion

829.	Paheli is curious to know whether application of a force can only change the speed of an object.
Answer» Answer :Application of a FORCE not only changes the speed of an object, but5 also the direction of MOTION of an object, i.e. a force can BRING about a change in the STATE of motion of an object.

Discussion

830.	Ignition temperature is the temperature above which the material cannot catch fire.
Answer» ANSWER :F

Discussion

831.	you know that a coin orpen falls to the ground when it slips off your hand. Leaves and fruis also fall to the ground when they get detached from the plant. Have you ever wondered why it is so?
Answer» Answer :A COIN or pen falls to the ground when it slips off our hand and EVEN leves and FRUITS FALL to TH eground.

Discussion

832.	explain. Force acting on a unit area is called pressure.
Answer» SOLUTION :N//A

Discussion

833.	When there is a_____between a magnet and a conductor, an EMF is induced in the conductor.
Answer» ANSWER :RELATIVE MOTION

Discussion

834.	Fill in the blanks : If still images of a moving object are flashed on the eye at a rate faster than________per second, then the eye perceives this object as ________.
Answer» ANSWER :16;MOVING

Discussion

835.	How does vacuum affect sound?
Answer» ANSWER :Sound cannot TRAVEL in VACUUM, i.e. in a SURROUNDING where there is no air.

Discussion

836.	Both sound and light waves can be propagated through
Answer» VACUUM air Both (a) and (B) NONE of the above Answer :B

Discussion

837.	In which direction does the force of friction and the applied force acts?
Answer» Opposite Same Upward Downward Answer :A

Discussion

838.	When the pressure increased,
Answer» melting POINT of ICE decreases and BOILING point of WATER increases. Melting point of ice and boiling point of water decreases. melting point of ice and boiling point of water increases. melting point of ice increases and boiling point of water decreases. Answer :A

Discussion

839.	What are the differencesbetween the flow of electric current through metal conductors andelectrolytes?
Answer» Solution :COMPARE the ELECTRIC current carriers in conductors and ELECTROLYTES. What is the role of electrodes in anelectrolyte? How do the ANIONS andcations move insidean ELECTROLYTE? Compare it with the movement of electrons in conductors.

Discussion

840.	The process of electrolysis is used in _______ .
Answer» GOLD covering metallurgy ELECTRIC printing All the above Answer :D

Discussion

841.	What will happen if the copper plate in Activity 14.7 is replaced by a carbon rod connected to the negative terminal of the battery?
Answer» Answer :If the copper PLATE in Activity 14.7 is REPLACED by a CARBON rod, a coating of copper on carbon rod GET deposited, i.e. electroplating of carbon has occurred.

Discussion

842.	Gasoline(explosive)transport trucksgenerallycarry long chains of metal hanging down and touching the ground. Why?
Answer» SOLUTION :What happens to the charge on a body when it is connected to the GROUND? What is the consequence if a GASOLINE transport truckis charged by FRICTION?

Discussion

843.	The harmful gases present in the exhaust should be removed by using________in vehicles.
Answer» ANALYTIC convertor pollutant convertor substrative convertor Catalytic convertor Answer :D

Discussion

844.	Does sound travel in liquids?
Answer» ANSWER :YES,SOUND TRAVELS in LIQUIDS.

Discussion

845.	The essential(s) for combustion is (are)
Answer» a combustile material. the PRESENCE of oxygen ignition TEMPERATURE of the substance All the above Answer :D

Discussion

846.	How is wheel or rolling effective?
Answer» Answer :Wheel or ROLLING HELPS in REDUCING friction.

Discussion

847.	When an iron bar is magnetised, there will be a slight increases in its length. Explain.
Answer» Solution :Will the molecular MAGNET ALIGN in the same DIRECTION when an iron BAR is MAGNETIZED ?

Discussion

848.	If the melting point of ice at a give place is 0^(@)C, the atmospheric pressure at the place is ______.
Answer» SOLUTION :76 CM of HG

Discussion

849.	Explain why a person falling from certain height on a hard surface gets hurt more seriously than when he falls on a soft surface.
Answer» Solution :FORCE EXERTED by HARD surface on the MAN is more than the one exerted by soft surface.

Discussion

850.	What is Cassiopeia?
Answer» Answer :Cassiopeia is a prominent constellation which APPEARS like a distorted LETTER W or M in the NORTHERN SKY. It is visible during WINTER in the late evening.

Discussion

Explore topic-wise InterviewSolutions in .

A block of weight 100 N and dimenions 50 cm x 30 cm x 10 cm rests on a table in three different positions with its base as (a) 50 cm x 30 cm, (b) 30 cm x 10 cm, (C) 50 cm x 10 cm. Calculate the pressure exerted in each case.

What is lightning conduction? How does it work?

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

What is electrostatic force?

Can liquids conduct eIectricity?

In the electrical method of magnetization, the polarity of the end in which current flows in clockwise direction

Which one of the following statements is true ?

A tuning fork is excited first in air and then in water. In which case is the amplitude more ? Explain.

Calculate the kinetic energy of a 20 kg wooden cart moving with a speed of 5 m/s. Calculate the kinetic energy again when the speed is doubled.

Fill in the blanks: Common salt when dissolved in distilled water makes it a good ___ of electricity.

What is voice box?

How can a magnet be demagnetized ?

State whether the following statements are true or false : After the full moon day,the sunlit part visible from the Earth decreases in size everyday.

Can you explain now why shoulder bags are provided with broad straps and not thin strap? And, why the tools meant for cutting and piercing always have sharp edges?

Behind the pupil of the eye is a lens which is thicker in the centre. What kind of lens is thicker at the centre?

Explain the working principle of hydraulic press using Pascal's law.

How do you come to know that a 'period' is over in your school?

Take a metre scale or a long metal rod and hold its one end to your ear. Ask your friend to gently scratch or tap at the other end of the scale. Can you hear the sound of scratching? Ask your friends around you if they were able to hear the same sound?

Since muscular force can be applied only when it is in contact with an object, it is also called a contact force. Are there other types of contact forces?

What do you mean by hearing?

The power of a solar panel depends on (A) the arrangment of the solar cells in it. (B) the extent of surface area of the solar cell.

If the radius of curvature of a convex mirror is 30 cm, what would be its focal length?

The distance betweent he LFP and UFP of a thermometer is 18 cm. the readint on the thermometer in Fahrenheit scale when the length of the mercury thread is 8 cm is____

What is the density of milk if 1 mL of milk has a mass of 1.03 g?

Fill in the blanks : The upper most layer of the earth is called______.

the process of transferring charge from a charged object to the earth is called______.

Gases do not have rigidity. Select the reason from the following .

Paheli is curious to know whether application of a force can only change the speed of an object.

Ignition temperature is the temperature above which the material cannot catch fire.

you know that a coin orpen falls to the ground when it slips off your hand. Leaves and fruis also fall to the ground when they get detached from the plant. Have you ever wondered why it is so?

explain. Force acting on a unit area is called pressure.

When there is a_____between a magnet and a conductor, an EMF is induced in the conductor.

Fill in the blanks : If still images of a moving object are flashed on the eye at a rate faster than________per second, then the eye perceives this object as ________.

How does vacuum affect sound?

Both sound and light waves can be propagated through

In which direction does the force of friction and the applied force acts?

When the pressure increased,

What are the differencesbetween the flow of electric current through metal conductors andelectrolytes?

The process of electrolysis is used in _______ .

What will happen if the copper plate in Activity 14.7 is replaced by a carbon rod connected to the negative terminal of the battery?

Gasoline(explosive)transport trucksgenerallycarry long chains of metal hanging down and touching the ground. Why?

The harmful gases present in the exhaust should be removed by using________in vehicles.

Does sound travel in liquids?

The essential(s) for combustion is (are)

How is wheel or rolling effective?

When an iron bar is magnetised, there will be a slight increases in its length. Explain.

If the melting point of ice at a give place is 0^(@)C, the atmospheric pressure at the place is ______.

Explain why a person falling from certain height on a hard surface gets hurt more seriously than when he falls on a soft surface.

What is Cassiopeia?

Fill in the blanks : If still images of a moving object are flashed on the eye at a rate faster thanper second, then the eye perceives this object as .