821 + Interview Questions in Physics in Class 7

1.	The method of measuring distance by forming a ______ is called tringulation method.
Answer» SOLUTION :The method of measuring distace by forming a trinangle is CALLED triangulation method.

Discussion

2.	Assertion: Metals are good conductors of electricity Reason:Metals conduct electricity in solid as well as in molten state
Answer» ANSWER :TRUE

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3.	Explain how will you change the time period of a simple pendulum.
Answer»

Discussion

4.	Describe the experimental method to determine the time period of a simple pendulum.
Answer»

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5.	The image formed by a plane mirror is real. True/False
Answer» ANSWER :F

Discussion

6.	Equal volumes of different liquids expand by different amounts when they are heated to the same rise in temperature.
Answer» ANSWER :T

Discussion

7.	Faster mode of transmisson of heat is ______.
Answer» SOLUTION :RADIATION is the FASTEST mode of TRANSMISSION of heat

Discussion

8.	The primary colours are red, blue and green.
Answer» ANSWER :T

Discussion

9.	A neutral body means a body with no charged par-ticles onit.
Answer» SOLUTION :A Neutral BODY consists of bot POSITIVELY charged and negatively changed particles. The body is neutralbecause the TOTAL positively charge is equal to the total negative charge.

Discussion

10.	In which of the following the pricipleof 'chemical effect of electricity' is not used ?
Answer» Telephone Purification of metals Electroplating Electro typing Answer :A

Discussion

11.	Which effect of electricity is used in electrotype set-ting ? Discuss.
Answer» Solution :In the newspaper press, a page is composed using ORDINARY types. Moulds of letters first prepared by using wax and graphite powder is spread over it to make it to conduct electricity. This is used as a cathode in the ELECTROLYSIS of copper sulphate. A piece of copper is used as the anode. A thick plating of copper is obtained and the wax INSIDE it is MELTED and removed. These copper letters are used to print thousand of copies of the newspapers. This is CALLED electrotype setting.

Discussion

12.	Tools used to make article or to repair them are called _________
Answer» Solution :Tool USED to make articles or to REPAIR them are CALLED workshop tools

Discussion

13.	Larger is the amplitude, feeble is the sound
Answer» ANSWER :F

Discussion

14.	Usually we use two different types of sockets (a) two-pin socket and (b) three-pin socket. What purpose does the thrid pin in a three-pin socket serve ?
Answer» Solution :SOCKETS are provided to connect movable ELECTRICAL appliances. We have TWO different types of sockets. (a) Two-pin socket : One pin a connected to a live wire and other pin is connected to a neutral wire. (b) Three-pin socket : One pin of connected to a live wire, second pin is connected is essential to GROUND leakage current or the unwantedcurrent that FLOWS accidentally through theouter cover of the appliance.

Discussion

15.	Convert 23m^(3) to cm^(2)
Answer» SOLUTION :`30000 CM^(2)`

Discussion

16.	Which of the following is (are) converging mirror (s)?
Answer» CONVEX MIRROR Concave mirror Plane mirror Both (a) and (B) ANSWER :B

Discussion

17.	Sound can travel in........
Answer» SOLUTION : a MEDIUM SOLID, LIQUID or GAS

Discussion

18.	A girl runs along a circular track of radius 5 m starting from point A. What will be the distance travelled by her and speed if she stops halfway at B in 400 s?
Answer» Solution :If the girl STOPS halfway through, her distance WOULD be half the circumference, which is EQUAL to `(2 XX pi x r)//2 = 3.14 xx 5 = 15.7 m` TIME = 400s `"Speed" = ("Distance travelled")/("Time taken ")=15.7//400= 0.039 m//s`

Discussion

19.	A girl runs along a circular track of radius 5 m starting from point A. What will be the distance travelled by her and speed if she comes back to the initial position in 300 s
Answer» Solution :SINCE the girl comes BACK to the original position, her distance WOULD be the circumference of the `2 x pi xx R= 2 xx 3.14 xx 5 = 31.4 m` Time = 300 s `"Speed" = ("Distance travelled")/("Time taken ")= 31.4//300= 0.1046m//s`

Discussion

20.	Describe about clinical thermometer
Answer» Solution :A device used to measure human or animal body temperature is called clinical thermometer. The range of clinical thermometer is from 35° to 42°C.The clinical thermometer can be electronic or mercury-based and shows the presence of a kink that allows steady HOLD of mercury so the VALUE can be READ for a LONGER time interval.

Discussion

21.	Which of these is not a workshop tool?
Answer» Hammer Tin cutter Scale SEED DRILL Solution :Seed drill is not WORKSHOP TOOL, it is an AGRICULTURAL tool

Discussion

22.	Which of the following is not a workshop tool?
Answer» DIVIDER Hammer Wooden PLANK Vice Solution :A woodn plank is an AGRICULTURE TOOL

Discussion

23.	The angle of incidence on a plane mirror is 30^@. The angle of reflection will be:
Answer» `30^@` `60^@` `15^@` `0^@` ANSWER :A

Discussion

24.	A red rose is seen in green light. It will appear
Answer» red blue YELLOW BLACK ANSWER :D

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25.	What are the appication of expansion of solid?
Answer»

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26.	Match the following:
Answer» Solution :(a)-(V), (b)-(i), (c)-(iv), (d)-(ii), (E)-(III)

Discussion

27.	A magnetic needle placed near a current carrying conductor deflects due to the
Answer» HEATING effect of electric current. magnetic effect of electric current. chemical effect of electrical current. Both (b) and (c ) Solution :A magnetic NEEDLE placed close to a current CARRYING conductor deflects due to the magnetic effect of the electric current. Because the magnetic needle (or its FIELD) interacts with the magnetic field produced by the current carrying conductor it deflects.

Discussion

28.	Answer the following question Define temperatue
Answer»

Discussion

29.	Match the following
Answer» SOLUTION :(a)-(iii), (B)-(IV), (c)-(v), (d)-II), (e)-(i)

Discussion

30.	A wooden block is tied to a metallic rod of mass 100 g and immersed completely inwater. When the displaced water is collected in water.
Answer» Solution :Mass of the metallic rod = 100 g Volume of the metallic rod + volume of WOODEN BLOCK = 400 ml Density of the metallic rod = 5 g `cm^(-3)` Volume of the metallic rod =` massof the metallic rod/density of the rod`=`8/1=n^(3)/1,n^(3)=8, n=2` Volume of wooden the block = `400-20 = 380 cm^(3)` Mass FO the wooden block =`"mass"/"volume"=300/380=0.79" g "cm^(-3)`

Discussion

31.	What is a depolarizer and how does it work ?
Answer» Solution :When a voltaic cell is made to work for some TIME, a thin layer of hydrogen is formed AROUND the COPPER electrode. This restricts the further flow of charges through the electrolyte. Depolarizer is a substance used to get rid of this problem is in a voltaic cell. Depolaziers work as an OXIDIZING agent and they REACT with hydrogen and change it to water.

Discussion

32.	Match the following
Answer» SOLUTION :(a)-(V), (B)–(i), (C)-(iv), (d)-(ii), (e)-(III)

Discussion

33.	Whenthe screw used to fixed the object between the jaws is rotated in the anit-clockwise direction, boththe jaws of the vice move towards each other.
Answer» Solution :Whent EH screws are ROTATED in anit-clock wised direction, the movable JAW MOVES AWAY the fixed jaw.

Discussion

34.	The frequency is measured in hertz
Answer» ANSWER :T

Discussion

35.	The Zinc plate in a voltaic cell is usually coated with mercury to prevent polarization.
Answer» Solution :A MERCURY COATING is given to the zinc plate in a voltaic CELL to reduce 'local ACTION'.

Discussion

36.	If 103 cm^(3) of aluminium has a mass of 0.280 kg. Find its density in g//cm^(3)
Answer» SOLUTION :`2.7 g//cm^(3)

Discussion

37.	The speed of sound in water is :
Answer» `332 MS^(-1)` `1500 ms^(-1)` `5000 ms^(-1)` `1000 ms^(-1)` Answer :B

Discussion

38.	Raed the following statement and choose the correct option. (A) Moon is a luminous source of light. (B) A glow worm is a natural source of light.
Answer» Only A is true Only B is true Both A and B are true Both A and are FALSE SOLUTION :The moon is not a luminous SOURCE of light, it simply reflects the light which is incident on it. A GLOW worm is a natural source of light.

Discussion

39.	Why are the walls, roof, seats and steps, of a cinema theatre or auditorium covered with special material ?
Answer» Solution :In theatres, auditoria, BIG halls, etc., due to the REFLECTION of sound from the walls, the FLOOR and the ceiling, the music or the speech rendered BECOMES uninteresting or unintelligible. To avoid this problem, the windows, doors, etc., are covered with thick curtains and the seats and steps are covered with sound ABSORBING materials like carpets.

Discussion

40.	Answer the following question Define heat capacity
Answer»

Discussion

41.	SI unit of area is____
Answer» SOLUTION :SI UNIT of AREA is `m^(2)`.

Discussion

42.	Lightning is anautral phenomenon involving "_______" particles.
Answer» Solution :Lighting ISA neutral PHENOMENON INVOLVING CHARGED particles.

Discussion

43.	Which of the following is (are) true in the case of a plane mirror?
Answer» Objcet distance = image distance. Object size = image size. The image FORMED is virtual. All the above. Solution :The PHENOMENON which is RESPONSIBLE for vision is irregular REFLECTION.

Discussion

44.	Which of the followingis a bad conductor of electricity
Answer» gold copper alcohol living plant Answer :C

Discussion

45.	A student breaks a fused bulb, and then hears a sound of explosion. What could be the reason for this ? Explain.
Answer» Solution :Initially, inside the bulb, LOW pressure inert gases are PRESENT. When the STUDENT BREAKS the bulb, air gushes inside the bulb, and HENCE, sounds like an explosion is heard.

Discussion

46.	Rings made up of copper and ironare fixed as shown in the figure . On heating the rings explain what happens to them if the thickiness of the rings are negligible
Answer»

Discussion

47.	Anelectric bulb converst _____ energy to ____ energy.
Answer» Solution :An ELECTRIC bulb CONVERTS ELECTRICAL energy to LIGHT energy.

Discussion

48.	Medium is necessary for the transfer of heat by radiation.
Answer» ANSWER :F

Discussion

49.	Which of the followingagricultural tools is used to sow the seeds in a field?
Answer» Horrow Leveller Plough WOODED plank Answer :A

Discussion

50.	If we add a lump of ice to a tumbler containing water :
Answer» HEAT FLOWS from WATER to ICE heat flows from ice to water heat flows from water to ice if water is more heat flows from ice to water if ice is more. Answer :A

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

The method of measuring distance by forming a ______ is called tringulation method.

Assertion: Metals are good conductors of electricity Reason:Metals conduct electricity in solid as well as in molten state

Explain how will you change the time period of a simple pendulum.

Describe the experimental method to determine the time period of a simple pendulum.

The image formed by a plane mirror is real. True/False

Equal volumes of different liquids expand by different amounts when they are heated to the same rise in temperature.

Faster mode of transmisson of heat is ______.

The primary colours are red, blue and green.

A neutral body means a body with no charged par-ticles onit.

In which of the following the pricipleof 'chemical effect of electricity' is not used ?

Which effect of electricity is used in electrotype set-ting ? Discuss.

Tools used to make article or to repair them are called _________

Larger is the amplitude, feeble is the sound

Usually we use two different types of sockets (a) two-pin socket and (b) three-pin socket. What purpose does the thrid pin in a three-pin socket serve ?

Convert 23m^(3) to cm^(2)

Which of the following is (are) converging mirror (s)?

Sound can travel in........

A girl runs along a circular track of radius 5 m starting from point A. What will be the distance travelled by her and speed if she stops halfway at B in 400 s?

A girl runs along a circular track of radius 5 m starting from point A. What will be the distance travelled by her and speed if she comes back to the initial position in 300 s

Describe about clinical thermometer

Which of these is not a workshop tool?

Which of the following is not a workshop tool?

The angle of incidence on a plane mirror is 30^@. The angle of reflection will be:

A red rose is seen in green light. It will appear

What are the appication of expansion of solid?

Match the following:

A magnetic needle placed near a current carrying conductor deflects due to the

Answer the following question Define temperatue

Match the following

A wooden block is tied to a metallic rod of mass 100 g and immersed completely inwater. When the displaced water is collected in water.

What is a depolarizer and how does it work ?

Match the following

Whenthe screw used to fixed the object between the jaws is rotated in the anit-clockwise direction, boththe jaws of the vice move towards each other.

The frequency is measured in hertz

The Zinc plate in a voltaic cell is usually coated with mercury to prevent polarization.

If 103 cm^(3) of aluminium has a mass of 0.280 kg. Find its density in g//cm^(3)

The speed of sound in water is :

Raed the following statement and choose the correct option. (A) Moon is a luminous source of light. (B) A glow worm is a natural source of light.

Why are the walls, roof, seats and steps, of a cinema theatre or auditorium covered with special material ?

Answer the following question Define heat capacity

SI unit of area is____

Lightning is anautral phenomenon involving "_______" particles.

Which of the following is (are) true in the case of a plane mirror?

Which of the followingis a bad conductor of electricity

A student breaks a fused bulb, and then hears a sound of explosion. What could be the reason for this ? Explain.

Rings made up of copper and ironare fixed as shown in the figure . On heating the rings explain what happens to them if the thickiness of the rings are negligible

Anelectric bulb converst _____ energy to ____ energy.

Medium is necessary for the transfer of heat by radiation.

Which of the followingagricultural tools is used to sow the seeds in a field?

If we add a lump of ice to a tumbler containing water :

Anelectric bulb converst _ energy to energy.