821 + Interview Questions in Physics in Class 7

1.	Lightning
Answer» Solution :LIGHTING ISA neutral phenomenon involving CHARGED particles.

Discussion

2.	Heat transfer in liquids and gases is by.........
Answer» SOLUTION :CONVECTION

Discussion

3.	SI unit of speed is ________
Answer» SOLUTION :SI UNIT of speed is MS^(-1)`

Discussion

4.	Which is the most convenient form of energy?
Answer» ANSWER :ELECTRICAL

Discussion

5.	What happens to a light ray that is incident on a plane mirror normally?
Answer» SOLUTION :When a light RAY is incident on a plane mirror normally, the angle of incidence `anglei=0`. According to the laws of reflection, `anglei=angler`. So, the angle of reflection also must be zero. The reflected ray must travel ALONG the same path in the opposite direction.

Discussion

6.	{:("Column A","Column B"),(A."Real image",(" ")a."Concave mirror"),(B."Virtual image",(" ")b."Convex mirror"),(C."Inner surface of a spoon",(" ")c."Erect"),(D."Outer surface of a spoon",(" ")d."Inverted"):}
Answer» Solution :A-d All the REAL images are inverted. B-c All the virtual images are erect. Convex mirrors also FORMS virtual images. C-a INNER SURFACE of a SPOON behaves as a concave mirror. Outer surface of a spoon behaves as a convex mirror.

Discussion

7.	________ sound is used as a diagnostic tool in medical science.
Answer» SOLUTION :ULTRASOUND is used as a DIAGNOSTIC tool in medical science.

Discussion

8.	The physical state of a substance can be changed by
Answer» decreasing its temperature removing HEAT ENERGY from the substane giving heat energy tothe substacne both B and c Solution :Change of state of substacne is due to the change in HET energy

Discussion

9.	Selecte the odd one from the following list.
Answer» Hack-saw Tin cutter Vice Drilling tool Answer :C

Discussion

10.	Nichorome' is the material used to make heating elements.
Answer» SOLUTION :Nichrome is usually PREFERRED to make HEATING ELEMENTS.

Discussion

11.	When two bodies A and B are rubbed, they acquire charge by frication, If the charge on positive, then the charge on B is "_______".
Answer» ANSWER :NEGATIVE

Discussion

12.	when bulbs are conneted to the same source, the brightness of bulb connected in series is more than the brightness of identical bulbs connected in parallel.
Answer» SOLUTION :BULBS GLOW with more BRIGHTNESS when they are con-nected in PARALLEL.

Discussion

13.	{:(,"Column A",,, "Column B"),(A., "Amplitude", (), a., "Vocal cords"),(B., "Frequency", ( ), b., "Sound absorbing material."),(C., "Human beings", ( ), c., "Reciprocal of time period"),(D., "Carpets", ( ), d., "m"):}
Answer» ANSWER :A : DB : CC : AD : B

Discussion

14.	Image formed by a convex mirror is
Answer» VIRTUAL erect smaller in SIZE than the OBJECT All the above. Answer :D

Discussion

15.	Find the false statement about a cell.
Answer» Symbol of a cell is Longer line represents POSITIVE terminal Shorter line represents NEGATIVE terminal. Cell is a MAJOR SOURCE of ELECTRICAL energy. Solution :A cell is a source of electrical energy, but not a major source of electrical energy.

Discussion

16.	The image formed by a plane mirror can be obtained on a screen.
Answer» ANSWER :F

Discussion

17.	Three persons P_(1), P_(2) and P_(3) are at different points A, B and C, respectively as shown in the figure. Two persons P_(1) and P_(3) clap at the same time. Which among the following can be the minimum distance between P_(2) and P_(3) to hear the clap sound distinctly by P_(2)? (Take the velocity of sound in air as 330 ms^(-1))
Answer» <P>330 m 384 m 363 m 660 m Solution :Velocity of sound `'v' = 330 MS^(-1)` distance between `P_(1)` and `P_(2) = 330 m` So, time taken to hear the sound `t = (330)/(330) = 1 s` Human ear can hear TWO sounds separately only if they reach at interval of 1/10 of a second. So, the time taken by the sound from `P_(3)` to reach `P_(2)` is minimum of `1 + 1/10 = 1.1 s`. So, the distance between `P_(2)` and `P_(3) = t xx v` `= 1.1 xx 330 = 363 m.`

Discussion

18.	In a vice, screw is rotated in ____________direction to tighten the vice
Answer» SOLUTION :In VICE scresws arerotated in CLOCKWISE DIRECTION to TIGHTEN the vice

Discussion

19.	The hack-saw blad cannot be removed from a hack-saw
Answer» SOLUTION : We can REMOVE the hack-saw BLADE a hack-saw

Discussion

20.	A magnet is brought close to a current carrying con-ductor as shown in figure, then
Answer» it will be repelled by the CONDUCTOR. it will be attracte by the conductor it will not show any effect. it will be just DEFLECTED. Solution :When a current is allowed to pass through a con-ductor, it PRODUCES a magnetic field aroound it, and hence, when a magnet is brought CLOSER to it, it will be deflected by the field produced by the current carrying conductor.

Discussion

21.	The motion of the handle of the plough while ploughing is __________
Answer» to and fro translatory vibratory Cannot be determined Solution :When the farmer plough with a plough,depending on the HARDNESS of the land, he some times PULLS up and PRESSES down the handle,down the handle, hence, the MOTION of the handle of the plough while ploughing is to and fro (up and down)

Discussion

22.	on heating iron expands more than copper
Answer» SOLUTION :on HEATING COPPER EXPANDS more or POLISHED

Discussion

23.	Assertion (A): The musical notes produced by two musical instruments, like guitar and sitar are different even if the length and the thickness of the strings in both instruments are the same. Reason (R) : The difference in two sounds of equal pitch and loudness can be distinguished by a characteristic property called quality of sound ro timbre.
Answer» Both A and R are correct and R is the correct explanation of A. Both A and R are correct but R is not the correct explanation of A. A is correct and R is incorrect. Both A and R are incorrect. Solution :The MUSICAL notes produced by two musical instruments, like GUITAR and SITAR are different even if the length and the thickness of the strings in both the instruments are same because of the difference in the QUALITY of sound. So , A and R are correct and R is correct explanation

Discussion

24.	The normal temperature of human body is 37^@C. What will be its value on the Kelvin scale ?
Answer» SOLUTION :SINCE `t^@C` = (273 + t) K `37^@C` = (273 + 37) K = 310 K

Discussion

25.	Condensation point of a substance is numerically equal to _____.
Answer» SOLUTION :Condensation POINT of a SUBSTACNE is numerically equal to the BOILING point of the substacne

Discussion

26.	A car moves with a contant velocity m its average velocity is equal to its______
Answer» ANSWER :VELOCITY

Discussion

27.	The sound of loudness of sound in the range of 15 B - 16 B is
Answer» not audible just audible moderate painful to the ear Answer :D

Discussion

28.	A current carrying coil when suspended freely can rest in any direction.
Answer» ANSWER :FALSE

Discussion

29.	Assertion (A) Radiation is the fatest mode of transmissin of heat Reason (R ) : Conduction and convection require a medium for transmission of heat where as heat radiations can travel through vaccum .
Answer» both a and R are correct and r is the correct EXPLANATION of a both a and r are correct but ra is not the correct explanation of a a is correct and r is INCORRECT both a and r are incorrect Solution :RADIATION is the fastest mode of transmission of heatIt does not REQUIRE any medium as , it transmits heat in the form of electromageneitic waves .But conduction and convenction required a material medium for transmission of heat so A and R are correct but R is not the correct explanation of A

Discussion

30.	A car travels a distance of 75 km in 1.5 hours What is its speed ?
Answer» SOLUTION :`13.8 m//s`

Discussion

31.	A neutral body gets charged when it brought into contact with a charged body. This method of charg-ing a body is called.
Answer» charging by CONDUCTION charging by friction charging by Induction None of the above Solution :In charging by conduction method, a neutral BODY GETS charged when it is brought into contact with a charged body.

Discussion

32.	For each of theequation four choices have been provided. select the correct alternative Arrange the following substance in the increasing order of their thermal conductivity copper iron glass
Answer» GLASS, IRON, COPPER copper , iron , glass iron, glass, copper iron, copper ,glass Answer :a

Discussion

33.	The mass of a body does not change with change in _____.
Answer» ANSWER :PLACE and TIME

Discussion

34.	Bats make use of _____ waves.
Answer» ULTRASONIC SOUND INFRASONIC sound audible RANGE sound All the above Answer :A

Discussion

35.	The density of gold is 19g//cm^(3) find the volume of 0.095 kg
Answer» SOLUTION :`5CM^(3)`

Discussion

36.	To draw circles on the wood, ___________ is used
Answer» ANSWER :DIVIDERS

Discussion

37.	A hammer is made ofa soft metal
Answer» SOLUTION :A hammer is made of a HARD HEAVY metal.

Discussion

38.	Answer the following question what is evaporation?
Answer»

Discussion

39.	The frequency of oscillation of seconds pendulum is ______ HZ.
Answer» 0.5 2h 50 100 Solution :0.5 HZ

Discussion

40.	The substances which do not allow heat to travel through them easily are said to be _________ of heat
Answer» Solution :The materials which do not allow heat to travel through them EASILY are called bad CONDUCTORS of heat

Discussion

41.	A Switch is used to make or brake an electric circuit.
Answer» SOLUTION :Switch is a derive USED as maker or BREAKER of an electric CIRCUIT.

Discussion

42.	Answer the following question what is specific heat capacity ?
Answer»

Discussion

43.	Answer the following question What is heat?
Answer» Solution :Heat is a FORM of ENERGY which MAKES the substance hot.

Discussion

44.	Black substance absorbs and lose heat radiations faster
Answer» Solution :Black SUBSTANCES ABSORB and radiate HEAT energy at a FASTER rate

Discussion

45.	The normal temperature of human body is 37^@C. What will be its value on theFahrenheit scale?
Answer» Solution :From `""^@F = 9/5 C + 32` ` = 9/5 xx 37 + 32` ` = 66.6 + 32` ` = 98.6 ` THUS `37^@C = 98.6^@F`

Discussion

46.	Ultrasonic sound waves are used in _______
Answer» dishwashers MEDICAL diagnostics detection of flaws in MATERIALS All the above Solution :ULTRASONIC SOUND waves are used in (a) dishwashes (ultrasonic bath), (b) medical diagnostics, (C) detection of flaws in materials, etc.

Discussion

47.	The intensity of light at a distance 'r' from the axis of a long cylindrical source is inversely proportional to 'r'
Answer» increases DECRASES first increases and then decreases remains same Solution :The intensity of light decrases, when the distance from the SOURCE increases.

Discussion

48.	Bimetallic strip worked on the principal of ________
Answer» unequal EXPANSION of solids unequal contraction of solids EQUAL expansion of solids both a and b Solution :BIMETALLIC strip WORKD on the PRINCIPLE of unequal expansion (or contraction ) of metallic stirps with which is made of

Discussion

49.	A glass rod P is oberserved to be attracting an ebonite rod Q , then
Answer» P and Q are UNCHANGED bodies. both P and Q are CHARGED with identical charge. both P and Q are charged oppositely. either P is charged, or Q is charged. If both are charged, they are OPPOSITE in nature. Answer :D

Discussion

50.	A Volvo bus covers 240 km in three hours and a car covers 250 km in five hours. Which is faster?
Answer» Solution :Distance TRAVELLED by the Volvo bus = 240 km, TIME taken = 3 hours Speed `240//3 = 80 km//h` Distance travelled by the car = 250 km time taken =5h Speed `250//5= 50 km//h` The Volvo bus is FASTER.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Lightning

Heat transfer in liquids and gases is by.........

SI unit of speed is ________

Which is the most convenient form of energy?

What happens to a light ray that is incident on a plane mirror normally?

{:("Column A","Column B"),(A."Real image",(" ")a."Concave mirror"),(B."Virtual image",(" ")b."Convex mirror"),(C."Inner surface of a spoon",(" ")c."Erect"),(D."Outer surface of a spoon",(" ")d."Inverted"):}

________ sound is used as a diagnostic tool in medical science.

The physical state of a substance can be changed by

Selecte the odd one from the following list.

Nichorome' is the material used to make heating elements.

When two bodies A and B are rubbed, they acquire charge by frication, If the charge on positive, then the charge on B is "_______".

when bulbs are conneted to the same source, the brightness of bulb connected in series is more than the brightness of identical bulbs connected in parallel.

{:(,"Column A",,, "Column B"),(A., "Amplitude", (), a., "Vocal cords"),(B., "Frequency", ( ), b., "Sound absorbing material."),(C., "Human beings", ( ), c., "Reciprocal of time period"),(D., "Carpets", ( ), d., "m"):}

Image formed by a convex mirror is

Find the false statement about a cell.

The image formed by a plane mirror can be obtained on a screen.

In a vice, screw is rotated in ____________direction to tighten the vice

The hack-saw blad cannot be removed from a hack-saw

A magnet is brought close to a current carrying con-ductor as shown in figure, then

The motion of the handle of the plough while ploughing is __________

on heating iron expands more than copper

The normal temperature of human body is 37^@C. What will be its value on the Kelvin scale ?

Condensation point of a substance is numerically equal to _____.

A car moves with a contant velocity m its average velocity is equal to its______

The sound of loudness of sound in the range of 15 B - 16 B is

A current carrying coil when suspended freely can rest in any direction.

Assertion (A) Radiation is the fatest mode of transmissin of heat Reason (R ) : Conduction and convection require a medium for transmission of heat where as heat radiations can travel through vaccum .

A car travels a distance of 75 km in 1.5 hours What is its speed ?

A neutral body gets charged when it brought into contact with a charged body. This method of charg-ing a body is called.

For each of theequation four choices have been provided. select the correct alternative Arrange the following substance in the increasing order of their thermal conductivity copper iron glass

The mass of a body does not change with change in _____.

Bats make use of _____ waves.

The density of gold is 19g//cm^(3) find the volume of 0.095 kg

To draw circles on the wood, ___________ is used

A hammer is made ofa soft metal

Answer the following question what is evaporation?

The frequency of oscillation of seconds pendulum is ______ HZ.

The substances which do not allow heat to travel through them easily are said to be _________ of heat

A Switch is used to make or brake an electric circuit.

Answer the following question what is specific heat capacity ?

Answer the following question What is heat?

Black substance absorbs and lose heat radiations faster

The normal temperature of human body is 37^@C. What will be its value on theFahrenheit scale?

Ultrasonic sound waves are used in _______

The intensity of light at a distance 'r' from the axis of a long cylindrical source is inversely proportional to 'r'

Bimetallic strip worked on the principal of ________

A glass rod P is oberserved to be attracting an ebonite rod Q , then

A Volvo bus covers 240 km in three hours and a car covers 250 km in five hours. Which is faster?