885 + Interview Questions in Physics in Class 8 Page 3 InterviewSolution

101.	Many comets are known to appear periodically. One such comet is Halley's comet, which appears afternearly every 76years.It was last seen in 1986.Can you tell,when Halley's comet will be visible again?
Answer» ANSWER :HALLEY's COMET will be VISIBLE again in 2062 (1986+76) A.D

Discussion

102.	Which appears bigger, a football placed near you, or a football placed at a distance of 100 m?
Answer» Answer :A football PLACED NEAR US APPEARS bigger than a football placed at a distance of LOOM.

Discussion

103.	The main scale reading of a vernier calipers (1 M.S.D. = 1 mm) having least count 0.01 cm of the internal and external diameters of a hollow tube are 11 mm and 12 mm. the minimum thickness of the tube is _________.
Answer» 1 MM 0.1 mm 0.05 mm 0.5 mm Answer :C

Discussion

104.	Find the ratio of lengths of two pendula whose time periods are in the ratio 1 : 4
Answer» Solution :`l_(1) : l_(1) = T_(1)^(2) : T_(2)^(2) = (12)/(4^(2)) = 1 : 16`

Discussion

105.	60 MJ energy is produced on combustion of 2 kg of coal. Find how much energy is produced on burning 0.5 kgof coal. Also find the calorific value of coal.
Answer» Solution :(i) Definition of calorific avlue . (ii) Calorific value is constgant for a GIVEN substance. (iii) Q=mc (iv) `Q PROP m` (v) `30 kJ g^(-1) , 15 mJ`

Discussion

106.	When you call up your friend who is standing at a distance, your friend is able to heir your voice. How does the sound travel to her?
Answer» Answer :When I call up a friend STANDING at a distance, he/she is ABLE to hear my VOICE as my SOUND travels to her through air.

Discussion

107.	Arrange the following steps in properr sequence for the construction and calibration of celsium thermometer. (a) Lower fixing point is marked by immersing the bulb of the thermometer in melting ice taken in a funnel. (b). The distance between the two fixed points is called fundamental interval. It is divided into 100 equal divisions in Celsium scale. (c). Take a thick walled capillary tube with thin walled glass bulb and fill it with mercury with the help of a funnel. (d) mark the upper fixing point with the help of hypsometer. (e) Place the glass bulb in a hot oil bath while filling the mercury to remove the air bubbles.
Answer» c a d e b c e a d b c e a b d c d b e a Solution :The construction and calibration of a celsius thermometer involves the following STEPS. TAKE a thick walled capillary tube with thin walled glass bulb and fill the bulb with mercury using a funnel (c) from one end and while filling it with the mercury PLACE the glass bulb in a hot oil bath to remove the air bubbles (e), now mark the lower fixing POINT by placing the bulb in melting ice taken in a funnel (a). Mark the upper fixing point with the help of hypsometer. (d). The distance between the two fixed poitns is called fundamental interval. in celsium scale the fundamental interval is divided into 100 equal divisions and it is calibrated (b).

Discussion

108.	A spring balance is attached to a lever of negligible mass as shown in the diagram. A body of mass 10 kg_(wt) hangs from the lever. The reading of the spring balance is ______ kg_(wt)
Answer» 2 5 6 3.5 Answer :C

Discussion

109.	What is orbit?
Answer» ANSWER :Orbit is the definite path along which a planet REVOLVES around the SUN.

Discussion

110.	Whyare magnets with concave shaped poles used in a D.C. motor?What happens if magnets with flat poles are used in it ?
Answer» Solution :How do the MAGNETIC LINES of force passing through the magnetic field change as the shape of the magnet changes ? How do the magnetic lines forces pass through the magnetic field if the magnetic POLES are FLAT ? How should the magnetic lines of force pass through a magnetic field to PRODUCED more turning effect in an armature ?

Discussion

111.	Do liquids and gases also excert pressure? Does it depend on the area on which the force acts?
Answer» ANSWER :Yes, liquids and GASES ALSO excert PRESSURE. No, the pressure excerted by liquids and gases does not depend on the AREA on which the force acts.

Discussion

112.	How can electrical be transferred from one object to another?
Answer» ANSWER :ELECTRICAL charge can be transferred from one object to another through a METAL CONDUCTOR.

Discussion

113.	What happends to the shape of a ball of dough when it is rolled to make a chapati?
Answer» ANSWER :The ball of DOUGH is FLATTENED when it is ROLLED to make a chapati, thus changing its SHAPE.

Discussion

114.	A bar magnet is moved over a steel bar as shown in the figure. Choose the correct alternative from the following
Answer» The end X becomes north pole if 'p, is south pole whne MOVED from the end x to y. the end y will BECOME a south pole IFP is south pole and moved from the end y to x. the end x will be a south pole if 'p' is a south pole and moved from x to y both (B) and (C) Answer :D

Discussion

115.	Which of the following is true regarding solenoid ? (A) strength of the magnetic field is independent of the material on which the coil is wound. (B) when the coil is wound around a soft iron core, it behaves like a temporary magnet.
Answer» Only A Only B Both A and B None of the above Answer :B

Discussion

116.	The pair of physical quantities having the same units are
Answer» stress and pressure. thrust and pressure. weight and stress. weight and pressure. Solution :The force ACTING on a UNIT AREA is called stress. `THEREFORE` The unit of stress and pressure are same.

Discussion

117.	The speed of light in air is 3 xx 10^8 m/s and the speed of light in glass is 2 xx 10^8 m/s. What isthe refractive index of glass?
Answer» ANSWER :1.5

Discussion

118.	State whether the following statement is true or false: Force of friction always acts in a direction opposite to the direction of motion of the object.
Answer» ANSWER :1

Discussion

119.	Observe this constellation for a few hours. Do you find any change in its position? You will observe that the shape of the constellation remains the same. You will find that the constellationappears to move in the sky from east to west.
Answer» Answer :YES, the POSITION of the constellation appears to change from EAST to WEST in the sky.

Discussion

120.	Give two examples each of situations in which you push or pull to change the state of motion of objects.
Answer» Answer :Example of SITUATION when we push or CHANGE the state of MOTION of objects are :(i) When we push a box, we change its SPEED.(ii) When a ball is HIT with a bat, it changes the direction of motion of the ball.

Discussion

121.	In the following statements, tick 'T' against those which are true, and 'F' against those which are false. Sound cannot travel in vacuum. (T/F)
Answer»

Discussion

122.	In the following statements, tick 'T' against those which are true, and 'F' against those which are false. The number of oscillations per second of a vibrating object called its time period. (T/F)
Answer»

Discussion

123.	In the following statements, tick 'T' against those which are true, and 'F' against those which are false. For, human ears, the audible range is 20 Hz to 20,000 Hz. (T/F) .
Answer»

Discussion

124.	In the following statements, tick 'T' against those which are true, and 'F' against those which are false. If the amplitude of vibration is large, sound is feeble. (T/F)
Answer»

Discussion

125.	In the following statements, tick 'T' against those which are true, and 'F' against those which are false. Unwanted or unpleasant sound is termed as music. (T/F)
Answer»

Discussion

126.	In the following statements, tick 'T' against those which are true, and 'F' against those which are false. The lower the frequency of vibration, the higher is the pitch. (T/F)
Answer»

Discussion

127.	In the following statements, tick 'T' against those which are true, and 'F' against those which are false. Noise pollution may cause partial hearing impairment. (T/F)
Answer»

Discussion

128.	The bell jar experiment shows that
Answer» sound cannot TRAVEL through VACUUM sound can travel through gas sound can travel through vacuum velocity of sound is least in gases Solution :Bell jar experiment SHOWS that sound requires a medium for its PROPAGATION and cannot travel through vacuum

Discussion

129.	State whether the following statements are true or false : The outer coat of the eye is white.
Answer» ANSWER :1

Discussion

130.	What do you mean by remote sensing?
Answer» Answer :The PROCESS of COLLECTING infonnation from a DISTANCE is KNOWN as remote SENSING.

Discussion

131.	If the frequency of vibration is high, the sound produced will have __________ pitch.
Answer» high low medium same Answer :B

Discussion

132.	100 ml of liquid A (density = 1200 kg m ^(-3)) and 100 g of liquid B (density = 0.8 g cm^(-3)) are mixed to form a homogeneous mixture. Assuming that tow liquid do not chemically react with each other, find density of the resultant mixture.
Answer» Solution :(i) DENSITY of MIXTURE = `("total mass")/("total VOLUME")` (II) `(44)/(45)G cm^(-3)`

Discussion

133.	Two similar bar magnets P and Q each of magnetic moment M, are taken,. If P is cut along its axial line and Q is cut along its equatorial line, all the four pieces obtained have
Answer» Solution :Pole strength decreases when the area of cross-section of the BAR magnet is REDUCED and the crouding of iron PIECES depends on the pole strength.

Discussion

134.	What do you mean by illuminated objects? Give examples.
Answer» Answer :The objects which do not have light of their own and SHINE in the light of other luminous objects are called ILLUMINATED objects. For example, moon, PLANETS, chair, BOOK, etc.

Discussion

135.	In winters when the lakes start feezing, the weather becomes very pleasant in the surrounding region. Explain.
Answer» Solution :In WINTER, when the LAKES starts freezing, the what happens to water? When water becomes ice, will it release heat ENERGY EQUAL to the latent heat of fusion at `0^(@)C`? Will that heat energy make the CLIMATE o the surrounding region very pleasant.

Discussion

136.	Assertion (A) : A child produces a higher pitched sound compared to that of an adult Reason (R): Pitch depends on the frequency of sound.
Answer» A and R are correct and R is the correct explanation of A A and R are correct but R is not the correct explanation of A A is correct but R is not correct Both A and R are not correct Solution :A CHILD produces a higher pitched sound COMPARED to that of an adult. Because pitch depends on the length and thickness of a vibrating body, i.e., VOCAL cord in this case. So, A is correct The pitch depends on the FREQUENCY of sound. R is also correct but not the correct explanation is A

Discussion

137.	Name the seismic zones in India.
Answer» Answer :The SEISMIC zones in India are :KASHMIR, WESTERN and Central HIMALAYAS.

Discussion

138.	A, B and C are three indenticalmetallic spheres havingpositive, negative and positive charges, respectively.The deficiency or excess of electrons present in A, B and C are 10, 20 and 31, respectively. Initiallythe spheres A and B are brought in contact and then B and C are brought together. Determine the magnitude andnature of charge present on the bodies after bringingthem in contact. (Take charge of electorn as 1.6xx10^(-19)C ).
Answer» Solution :(i) CHARGE each conductor when they brought together `= (q_(1)+q_(2))/(2)` where `q_(1)` and `q_(2)` are the charge on each body. (ii)`A RARR -8 xx 10^(-19)C` B and C + 20.8`xx10^(-19)C`

Discussion

139.	Fill in the blanks : ________help in converting sllding into rolling in machines.
Answer» ANSWER :BALL BEARING

Discussion

140.	Mark the following statements as true (T) or false (F) . Pole star is a member of the Solar System.
Answer» ANSWER :F

Discussion

141.	Explain why sportsmen use shoes with spikes.
Answer» Answer :SPORTSMEN use shoes with spikes as it INCREASES FRICTION to GIVE them a better grip on the ground and prevent them from SLIPPING while running or playing.

Discussion

142.	What happens when you press a rubber ball placed on a table?
Answer» ANSWER :When we PRESS a rubber BALL PLACED on a table, its shgape changes.

Discussion

143.	Suppose you are outside your home and an earthquake strikes. What precaution would you take to protct yourself?
Answer» ANSWER :if we are outdoors when an EARTHQUAKE strike, then we should follow certain SAFETY guidelines such as :

Discussion

144.	If P, V, and d are the pressure, Volumne and density of a given mass of gas at constant temperature, choose the correct option.
Answer» <P>`palpha(1)/(d)` `p ALPHA d` `p alpha(1)/(V )` Both a and c Solution :According to Boyle's at constant temperature `p alpha (1)/(v)` But `d=(m)/(v) " or" v=(m)/(d)` when m is constant `p alpha (1)/(m_(d)), p alpha d`

Discussion

145.	When equal amount of heat is supplied to two different substnace 'A' and 'B', the riese in temperature with time is graphically represented as follows. Choose the correct statement.
Answer» If MASSES of 'A' and 'B' are equal, specifici heat of 'A' is equal to specific heat of 'B' If mass of 'A' is greater than mass of 'B' the specific heat CAPACITY of 'A' is greater than the specific heat capacity of 'B'. Heat capacity of A is LESS heat capacity of B. None of these Answer :C

Discussion

146.	The girls in the two situations whown here are applying force on each other. Is it true for the man and the cow?
Answer» Answer :y6es, the man and the cow are ALSO applying FORCE on each other.

Discussion

147.	I have seen fountains of water coming out of the leaking joints or holes in ipies supplying water. Is it not due to the pressure excerted by water on the walls of the pipes?
Answer» ANSWER :Yes, FOUNTAINS of water come out of the leaking joints or holes in PIPES SUPPLYING water DUE to the pressure excerted by water on the walls of the pipe.

Discussion

148.	In which of the following cells, carbon is not used as positive electrode ?
Answer» Leclanchecell LEAD-acid storage battery. Dry cell None of the above Solution :Carbon is notused as POSITIVE ELECTRODE in lead acid battery.

Discussion

149.	The speed of light in air is 3xx10^8 m/s. Find its speed in diamond if the refractive index of diamond is 2.42 .
Answer» Solution :We know that `N="SPEED of light in air or vacuum (c )"/"speed of light in the medium (V )"` Here , n=2.42 and `c=3xx10^8` m/s `2.42=(3xx10^8)/v` `v=(3xx10^8)/2.42 =1.24 xx 10^8` m/s Thus, the speed of light in diamond has REDUCED considerably.

Discussion

150.	Choose the correct option(Multiple choice questions): ___ water cannot conduct electricity.
Answer» Salt Distilled Tap Rain Answer :B

Discussion

Explore topic-wise InterviewSolutions in .

Many comets are known to appear periodically. One such comet is Halley's comet, which appears afternearly every 76years.It was last seen in 1986.Can you tell,when Halley's comet will be visible again?

Which appears bigger, a football placed near you, or a football placed at a distance of 100 m?

The main scale reading of a vernier calipers (1 M.S.D. = 1 mm) having least count 0.01 cm of the internal and external diameters of a hollow tube are 11 mm and 12 mm. the minimum thickness of the tube is _________.

Find the ratio of lengths of two pendula whose time periods are in the ratio 1 : 4

60 MJ energy is produced on combustion of 2 kg of coal. Find how much energy is produced on burning 0.5 kgof coal. Also find the calorific value of coal.

When you call up your friend who is standing at a distance, your friend is able to heir your voice. How does the sound travel to her?

A spring balance is attached to a lever of negligible mass as shown in the diagram. A body of mass 10 kg_(wt) hangs from the lever. The reading of the spring balance is ______ kg_(wt)

What is orbit?

Whyare magnets with concave shaped poles used in a D.C. motor?What happens if magnets with flat poles are used in it ?

Do liquids and gases also excert pressure? Does it depend on the area on which the force acts?

How can electrical be transferred from one object to another?

What happends to the shape of a ball of dough when it is rolled to make a chapati?

A bar magnet is moved over a steel bar as shown in the figure. Choose the correct alternative from the following

Which of the following is true regarding solenoid ? (A) strength of the magnetic field is independent of the material on which the coil is wound. (B) when the coil is wound around a soft iron core, it behaves like a temporary magnet.

The pair of physical quantities having the same units are

The speed of light in air is 3 xx 10^8 m/s and the speed of light in glass is 2 xx 10^8 m/s. What isthe refractive index of glass?

State whether the following statement is true or false: Force of friction always acts in a direction opposite to the direction of motion of the object.

Observe this constellation for a few hours. Do you find any change in its position? You will observe that the shape of the constellation remains the same. You will find that the constellationappears to move in the sky from east to west.

Give two examples each of situations in which you push or pull to change the state of motion of objects.

In the following statements, tick 'T' against those which are true, and 'F' against those which are false. Sound cannot travel in vacuum. (T/F)

In the following statements, tick 'T' against those which are true, and 'F' against those which are false. The number of oscillations per second of a vibrating object called its time period. (T/F)

In the following statements, tick 'T' against those which are true, and 'F' against those which are false. For, human ears, the audible range is 20 Hz to 20,000 Hz. (T/F) .

In the following statements, tick 'T' against those which are true, and 'F' against those which are false. If the amplitude of vibration is large, sound is feeble. (T/F)

In the following statements, tick 'T' against those which are true, and 'F' against those which are false. Unwanted or unpleasant sound is termed as music. (T/F)

In the following statements, tick 'T' against those which are true, and 'F' against those which are false. The lower the frequency of vibration, the higher is the pitch. (T/F)

In the following statements, tick 'T' against those which are true, and 'F' against those which are false. Noise pollution may cause partial hearing impairment. (T/F)

The bell jar experiment shows that

State whether the following statements are true or false : The outer coat of the eye is white.

What do you mean by remote sensing?

If the frequency of vibration is high, the sound produced will have __________ pitch.

100 ml of liquid A (density = 1200 kg m ^(-3)) and 100 g of liquid B (density = 0.8 g cm^(-3)) are mixed to form a homogeneous mixture. Assuming that tow liquid do not chemically react with each other, find density of the resultant mixture.

Two similar bar magnets P and Q each of magnetic moment M, are taken,. If P is cut along its axial line and Q is cut along its equatorial line, all the four pieces obtained have

What do you mean by illuminated objects? Give examples.

In winters when the lakes start feezing, the weather becomes very pleasant in the surrounding region. Explain.

Assertion (A) : A child produces a higher pitched sound compared to that of an adult Reason (R): Pitch depends on the frequency of sound.

Name the seismic zones in India.

Fill in the blanks : ________help in converting sllding into rolling in machines.

Mark the following statements as true (T) or false (F) . Pole star is a member of the Solar System.

Explain why sportsmen use shoes with spikes.

What happens when you press a rubber ball placed on a table?

Suppose you are outside your home and an earthquake strikes. What precaution would you take to protct yourself?

If P, V, and d are the pressure, Volumne and density of a given mass of gas at constant temperature, choose the correct option.

When equal amount of heat is supplied to two different substnace 'A' and 'B', the riese in temperature with time is graphically represented as follows. Choose the correct statement.

The girls in the two situations whown here are applying force on each other. Is it true for the man and the cow?

I have seen fountains of water coming out of the leaking joints or holes in ipies supplying water. Is it not due to the pressure excerted by water on the walls of the pipes?

In which of the following cells, carbon is not used as positive electrode ?

The speed of light in air is 3xx10^8 m/s. Find its speed in diamond if the refractive index of diamond is 2.42 .

Choose the correct option(Multiple choice questions): ___ water cannot conduct electricity.