885 + Interview Questions in Physics in Class 8 Page 18 InterviewSolution

851.	Does it mean that the application of a force would always result in a change in the state of motion of the object?
Answer» ANSWER :No, the application of a force would not ALWAYS result in a change inthe STATE of motion of the OBJECT.

Discussion

852.	State whether the following statement are true or false : Lightning is also an electric spark.
Answer» ANSWER :1

Discussion

853.	How is seeing made possible?
Answer» Answer :Seeing is MADE possible through the sense of sight and light. When light from an OBJECT enters our eyes, the object becomes VISIBLE to us.

Discussion

854.	The time taken by a vibrating body to move from one extreme position to the other extreme position is 0.1 s. If the distance between adjacent crests is 2 m, write the steps to determine the wave velocity in proper sequence (a) Determine the frequency of the wave (f) (b) Note down the wavelength (lamda) (c) Note down the time period (T) Determine the velocity of the wave as v = f lamda
Answer» a b c d b c a d d a b c d c b a Solution :Initially the WAVELENGTH `(LAMDA)` is NOTED (b). From the time PERIOD of oscillation the FREQUENCY (f) is determined (c,a) The velocity of the wave v is determined as velocity `v = f lamda (d)`

Discussion

855.	The angle between the geographical axis and the magnetic axis is 17^(@), then why does the value of angle of declination change from place to place ?
Answer» SOLUTION :DIFFERENCE between geographical axis and geographical meridian. Difference between MAGNETIC axis and magnetic meridian.

Discussion

856.	Which of these is a kind of contact force?
Answer» GRAVITATIONAL force Magnetic force Frictional force Electrostatic force Answer :C

Discussion

857.	What do you mean by celestial objects?
Answer» Answer :CELESTIAL OBJECTS are the objects observed in the sky such as the Sun , the STARS,themoon, the PLANETS and several other objects lik ecomets,meteors,asteroids,etc.

Discussion

858.	Recall also how difficult it is to move on a wet muddy tra ck, on wet marble floor. Can you imagine being able to walk at all if there were no friction?
Answer» ANSWER :No, WITHOUT FRICTION we will not be ABLE to WALK.

Discussion

859.	Fill in the blanks : To minimise friction, objects aregiven ________ .
Answer» ANSWER :SPECIAL SHAPE

Discussion

860.	If a glass prism is kept in a liquid of the same refractive index as that of glass, will the ray of light bend (Fig. B)? Complete the path of the ray of light.
Answer» Solution :Ray BENDS only if the refractive INDICES of the TWO MEDIUMS are DIFFERENT

Discussion

861.	What is a force? What can it do to bodies on which it is applied?
Answer» Answer :Any KIND of pull or push on an OBJECT is called force. Force can change the following things of the bodies on which it is applied :(i) the direction of motion of the object.(ii) The speed of the object.

Discussion

862.	When was the present system of Braille adopted?
Answer» ANSWER :The present system of Braille was ADOPTED in 1932.

Discussion

863.	The apparent weight of a floating body is equal to ______.
Answer» SOLUTION :N//A

Discussion

864.	Choose the correct option (Multiple choice questions) : In a plane mirror,________images of an object placed in front of it is formed.
Answer» two four one multiple Answer :C

Discussion

865.	State whether the following statements are true orfalse : We can increase or decrease friction according to our need.
Answer» ANSWER :1

Discussion

866.	What is the charge acquired by a rod when it is rubbed with silk?
Answer» Answer :When a GLASS ROD is RUBBED with SILK, it acquires a positive charge.

Discussion

867.	A copper wire of mass 20 g carries a current of 6.023 A. What fraction of the total number of free electrons present in copper wire flows through the cross-section of the copper wire in 2 s ? (gram atomic weight of copper = 63.5 g)
Answer» SOLUTION :(i) Number of ATOMS (n) = mass of the SUBSTANCE `xx` number of atoms in one gram. Number of electrons = n `xx` no. of electrons in each atom `i=(Q)/(t)` `q=n bar(e)` (II) ` (127)/(64xx10^(4))`

Discussion

868.	In an electromagnetic induction, what is the source of electric energy that causes induced current ?
Answer» Solution :How is the induced current DEVELOPED when a magnet MOVES TOWARDS the COIL ? What happens to the mechanical ENERGY that is used to move the magnet ?

Discussion

869.	In a new scale of temperature the lower fixed point is marked as 0 corresponding to the melting point of substance which is equal to 25^(@)C ad the upper fixed poitn is marked corresponding to the boiling point of a substance which is equal to 175^(@)C. the total length of scale between the UFP and LFP is divided into 200 equal parts. Determine the temperature in the new scale when the temperature of substance measrued by celsius scale thermometer is 50^(@)C
Answer» Solution :In the NEW scale of temperature, The lower fixed POINT (LFP)=MELTING Point of substance=0 units=`25^(@)C` The upper fixed point (LFP)=Boiling point of a SUBSTANT`=175^(@)C` The total length of the new scale=200units find out `50^(@)C=`how many units in new scale?

Discussion

870.	Which of the following is NOT a member of the Solar System?
Answer» An asteroid A satellite A constellation A comet Answer :C

Discussion

871.	When we pass the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to
Answer» PRESSURE of water gravity of the earth shape of RUBBER bulb. atmospheric pressure Answer :D

Discussion

872.	What is crescent moon?
Answer» Answer :Crescent MOON is the SMALL part of the moon visible in the sky either between a HALF moon and a NEW moon or between a new moon and a half moon.

Discussion

873.	What is the kinetic energy of a 45 kg rickshaw moving at 10 m/s?
Answer» SOLUTION :`KE=1/2mv^2`,m=45 kg , v=10 m/s `KE=1/2 XX 45xx(10)^2 = 1/2 xx 45xx10xx10` KE=2250 J or 2.25 kJ

Discussion

874.	Speak loudly for a while or sing a song or buzz like a bee. Put your hand on your throat as shown in Fig. Do you feel any vibrations?
Answer» Answer :Yes, we feel some vibration when we touch our THROAT while SPEAKING LOUDLY, or singing a SONG or BUZZING like a bee.

Discussion

875.	Do you wonder how a layer of one metal can be deposited on top of another?
Answer» Answer :By ELECTROPLATING,a LAYER of ONE metal can be deposited on TOP of ANOTHER?

Discussion

876.	The magnetic moment of a bar magnet 'A' and its length are twice that of another bar magnet 'B'. Arrange the following steps in sequential order to find the ratio of their pole strengths. (a) Write the given values of magnet moment (M) and magnetic length (2l) of the bar magnets A and B as M_(B)=2M_(A) and 2l_(B)=2(2l_(A)) (b) Write the expression for pole strength (m) for each magnet using m=M/(2l) (c) Divide the two expression to get the ratio of m_(A) to m_(B)
Answer» bac acb bca abc Solution :(a) WRITE the given values of MAGNET moment (M) and LENGTH (l) of the bar magnets A and B as `M_(B)=2M_(A)` and `2l_(B)=2(2l_(A))`(a) . (b) Write the expression for pole strength (m) for each magnet using m`=M/(2l) (b)`. (c) Dividing the two expression to GET the ratio of `m_(A)` to `m_(B)` (c)

Discussion

877.	The time period between one fullmoon to the next full moon,is slightly longerthan_______ days.
Answer» 27 30 `28frac{1}{2}` 29 Answer :D

Discussion

878.	What is the unit of measurement of loudness?
Answer» Answer :LOUDNESS is MEASURED in DECIBEL, which is EXPRESSED as dB.

Discussion

879.	State whether the following statements are true or false: Small amount of mineral salts present naturally in water are beneficial for human health.
Answer» ANSWER :1

Discussion

880.	A car moves along a straight path with variable velocity as shown in the figure. When the car is at possiting A, its velocity is 10 m s^(-1)and when it is atposition B, its velocity is 20 m s^(-1). If the cartakes 5 seconds of time to move from A to B, find theacceleration of the car.
Answer» Solution : Initial POSITION of the car at position`A=u=10 m s^(-1)` Final velocity of the car at position `B=v=20m s^(-1)` The charge in velocity of the car, `Deltav=v-u=20 m s^(-1)-10 m s^(-1)` `= 10 m s^(-1)` Time take taken for the car to MOVE from A to B, `Deltat=5S` `:.` Accelertion of the car, `a=(Deltav)/(Detlat)=(10 m s^(-))/(5s)` `2 m s^(-2)`

Discussion

881.	Explain different types of force.
Answer» ANSWER :CONTACT FORCE.Non-contact force.

Discussion

882.	In Class VII you have learnt that in the process of digestion the food gets pushed through the alimentary canal. Could it be a muscular force that does it? You also know that lungs expand and contract while we inhale and exhale air during breathing. Where are these muscles located which make breathing possible? Can you list a few more examples of the force excerted by the muscles in our body?
Answer» ANSWER :yes, in the process of digestion the FOOD gets PUSHED through the alimentary CANAL with the help of muscular force.

Discussion

883.	When the fast moving wind rotates the blades of a windmill is shaft rotates the armature inside the generator producing electric current.
Answer» ANSWER :T

Discussion

Explore topic-wise InterviewSolutions in .

Does it mean that the application of a force would always result in a change in the state of motion of the object?

State whether the following statement are true or false : Lightning is also an electric spark.

How is seeing made possible?

The angle between the geographical axis and the magnetic axis is 17^(@), then why does the value of angle of declination change from place to place ?

Which of these is a kind of contact force?

What do you mean by celestial objects?

Recall also how difficult it is to move on a wet muddy tra ck, on wet marble floor. Can you imagine being able to walk at all if there were no friction?

Fill in the blanks : To minimise friction, objects aregiven ________ .

If a glass prism is kept in a liquid of the same refractive index as that of glass, will the ray of light bend (Fig. B)? Complete the path of the ray of light.

What is a force? What can it do to bodies on which it is applied?

When was the present system of Braille adopted?

The apparent weight of a floating body is equal to ______.

Choose the correct option (Multiple choice questions) : In a plane mirror,________images of an object placed in front of it is formed.

State whether the following statements are true orfalse : We can increase or decrease friction according to our need.

What is the charge acquired by a rod when it is rubbed with silk?

A copper wire of mass 20 g carries a current of 6.023 A. What fraction of the total number of free electrons present in copper wire flows through the cross-section of the copper wire in 2 s ? (gram atomic weight of copper = 63.5 g)

In an electromagnetic induction, what is the source of electric energy that causes induced current ?

Which of the following is NOT a member of the Solar System?

When we pass the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to

What is crescent moon?

What is the kinetic energy of a 45 kg rickshaw moving at 10 m/s?

Speak loudly for a while or sing a song or buzz like a bee. Put your hand on your throat as shown in Fig. Do you feel any vibrations?

Do you wonder how a layer of one metal can be deposited on top of another?

The time period between one fullmoon to the next full moon,is slightly longerthan_______ days.

What is the unit of measurement of loudness?

State whether the following statements are true or false: Small amount of mineral salts present naturally in water are beneficial for human health.

A car moves along a straight path with variable velocity as shown in the figure. When the car is at possiting A, its velocity is 10 m s^(-1)and when it is atposition B, its velocity is 20 m s^(-1). If the cartakes 5 seconds of time to move from A to B, find theacceleration of the car.

Explain different types of force.

When the fast moving wind rotates the blades of a windmill is shaft rotates the armature inside the generator producing electric current.