9264 + Interview Questions in Physics in Class 10 Page 98 InterviewSolution

4851.	Twp lenses of power +12 D and -2 D are placed in contact. The focal length of the combination is
Answer» `+10` cm `+ 12.5` cm `+ 16.6` cm `+8.3` cm SOLUTION :Power P of lens combination `= P_(1) + P_(2) = + 12 D - 2 C = + 10 D` `therefore` Focal LENGTH of lens combination `f = (1)/(P) = + (1)/(10) m = + 0.1 m = + 10 cm`

Discussion

4852.	In the euqation of motion, x=at + bt^(2), the units of a and b are respectively
Answer» `m/s^(2)` `m/s, m/s^(2)` m/s, m/s none of these Solution :GIVEN, `x = at + BT^(2)` at and `bt^(2)` must have the same units as that of x. `:.` Units of a and b are `MS^(-1)` And `ms^(-2)`RESPECTIVELY

Discussion

4853.	Write the lens Formula.
Answer» Solution :Thelens maker .s formula is one such equation . It is GIVEN as `(1)/(F)=(mu-1)((1)/(R_(1))-(1)/(R_(2)))` where `mu` is the refractive index of the material of the lens, `R_(1) andR_(2)`are the radii of curvature of the two faces of the lens , f is the FOCAL length of the lens.

Discussion

4854.	The translational kinetic energy of gas molecules for 1 mol of gas is equal to
Answer» `(3)/(2)RT` `(2KT)/(3)` `(RT)/(2)` `(3KT)/(2)` ANSWER :A

Discussion

4855.	…………………is the important neurotransmitter released by neurons.
Answer» CEREBROSPINAL FLUID Axoplasm Acetylcholine All the above ANSWER :C

Discussion

4856.	At what common temperature a block of wood metal appear equally cold or hot when touched?
Answer» Solution :A BODY appear hot when TOUCHED if heat flows from body to our hand and vice-versa. If there is no flow of heat across body and hand, the body can not be identified while it is hot or COLD as bodies are in thermal equilibrium with our body. So both block of wood and metal MUST have the temperature of our body. `i.e., 37^(@)C`

Discussion

4857.	Cnidoblast:
Answer» Solution :CNIDOBLASTS are USED to inject the toxins in the BODY of prey. Their FUNCTION is characteristic in the animals BELONGING to. phylum Cnidaria.

Discussion

4858.	A bob of mass 0.1 kg hung from the ceiling of room by a string 2 m long is oscillating. At its mean position the speed of a bob is 1 ms^(-1). What is the trajectory of the oscillating bob if the string is cut when the bob is (i) At the mean position (ii) At its extreme position.
Answer» ANSWER :(i) PARABOLIC, (II) VERTICALLY DOWNWARDS

Discussion

4859.	A piece of wire of resistance R is cut into five equal parts. These parts are thenconnected in parallel. If the equivalent resistance of this combination is R., then the ratio R/(R.) is ………………. .
Answer» `1/25` `1/5` `5` `25` Solution :Here, the resistance of a piece of wire is R. This piece of wire is CUT into FIVE equal parts, so the resistance of eachpart would be `R/5`. Now, these five parts each having resistance of `R/5` are connected in parallel. The equivalent resistance R. of this combination is given by `1/(R.) =(1)/(R/5) + 1/(R/5) +1/(R/5) +1/(R/5) +1/(R/5)` `:. 1/(R.) = 5/R + 5/R +5/R + 5/R +5/R= (25)/R` `:.R/(R.) =2 5`

Discussion

4860.	Rayleigh's scattering is inelastic scattering.
Answer» Solution :CORRECT STATEMENT- Rayleigh's scattering is ELASTIC scattering.

Discussion

4861.	Lead nitrate solution is added to a tes tube containing potassium iodide solution. (a) Write the name and colour of the compound precipitated. (b) Write the balanced chemical equation for the reaction involved. (c ) Name the type of this reaction justifying your answer.
Answer» Solution :(a) Lead iodide. It has a yellow colour. (b) `Pb(NO_(3))_(2) + 2KI rarr PbI_(2) + 2KNO_(3)` (c ) Double DISPLACEMENT reaction. The cations have exchanged their anions.

Discussion

4862.	Give an example of a phenomenon where Tyndall effect can be observed.
Answer» SOLUTION :When a FINE beam of sunlight enters a SMOKE filled room through a small HOLE.

Discussion

4863.	Effective disaster management makes us well prepared for future. Explain why it is said like that.
Answer» Solution :(i) Disaster Management is achieving or time to time improving the ability to face the disasters through scientific and careful observations and analysis of data. (II) It INVOLVES collecting the information about intensity of disaster and probable sites of disaster through predictive intensity MAPS and hazard maps respectively. (iii) It also includesetting special training for disaster management. (iv) Preparedness is a PLAN chalked out so as to get the quick response from general PUBLIC and administration.

Discussion

4864.	Lactobacilli in Yoghurt industry:
Answer» SOLUTION :(1) Making yoghurt or CURDS from milk. (2) Acetyldehyde like compounds are formed due to action of Lactobacilli. (3) Giving characteristic FLAVOUR and TASTE to yoghurt.

Discussion

4865.	Do all vibrating bodies necessarily produce sound?
Answer» Solution :All vibrating bodies PRODUCE SOUND, but we cannot HEAR some of them, DUE to the limit of audible frequency.

Discussion

4866.	The numerical value of density in SI is n times its value in cgs system. The value of n is
Answer» 10 100 1000 `(1)/(1000)` ANSWER :C

Discussion

4867.	Name two main fossil fuels.
Answer» SOLUTION :COAL and PETROLEUM.

Discussion

4868.	List two methods of producing magnetic fields.
Answer» SOLUTION :Magnetic FIELD can be produced by (i) a NATURAL magnet (II) a CURRENT carrying conductors

Discussion

4869.	Which phenomena can you study using a glass prisms ?
Answer» SOLUTION :USING a glass PRISM,we canstudy two PHENOMENA : Refraction of Light , and Disparsion of Light.

Discussion

4870.	In the equation ""_6C^(14) to ""_7N^(14) +""_(-1)e^(0) which decay of radioactive carbon-14 results in the new nitrogen-14 atom ?
Answer» SOLUTION :BETA DECAY

Discussion

4871.	Free fall
Answer» SOLUTION :When a body FALLS towards the EARTH under the INFLUENCE of the Earth's gravity alone, its motion is called a free fall.

Discussion

4872.	The refractive index of ice is …………… .
Answer» 1.36 1.31 1.52 1.46 Answer :A::C

Discussion

4873.	Derive an expression for the effective resistance when three resistors are connected in (i) series (ii) parallel.
Answer» Solution :PARALLEL Connection : In Parallel connection of resistors there is same potential difference at the ends of the resistors. HENCE the voltage in the circuit is EQUAL to V. Let `I_(1),I_(2)andI_(3)` be the currents flowing through `R_(1),R_(2)andR_(3)` resistors respectively. Hence, we can write `I=I_(1)+I_(2)+I_(3).` According to the Ohm's law. `V_(1)=1_(1)R_(1),V_(2)=I_(2)R_(2),V_(3)=I_(3)R_(3)` here,`V=V_(1)=V_(2)=V_(3)` `thereforeV=I_(1)R_(1),V=I_(2)R_(2),V=I_(3)R_(3)` `rArrI_(1)=(V)/(R_(1)),I_(2)=(V)/(R_(2))andI_(3)=(V)/(R_(3))` `thereforeI=I_(1)+I_(2)+L_(3)` `rArr(V)/(R_(eq))=(V)/(R_(1))+(V)/(R_(2))+(V)/(R_(3))` `rArrcancel(V)xx(1)/(R_(eq))=cancel(V)[(1)/(R_(1))+(1)/(R_(2))+(1)/(R_(3))]` `rArr(1)/(R_(eq))=(1)/(R_(1))+(1)/(R_(2))+(1)/(R_(3))(" here " R_(eq)" is the equivalent resistance ")` `therefore` The equivalent resistance of a parallel combination is less than the resistance of each of the resistors.

Discussion

4874.	Why do the farmers fill their fields with water in winter.
Answer» SOLUTION :The fanners fill their fields with water in WINTER to protect thecrops from frost because, water due to its high specific heat CAPACITY does not allow the temperature in the SURROUNDING area of plants to FALL below `0^@C`.

Discussion

4875.	A free charged particles moves through a magnetic field the particle may undergo a change in :
Answer» SPEED Energy DIERCTION of MOTION None of these Answer :C

Discussion

4876.	The experimental arrangement correct order is : a. Keep the steel plate on the floor at the bottom of the tube. b) Mark the readings in cm along the tube. c. Take a long plastic tube of length nearly 200 cm which is be into half along the length. d. Place one end of the tube on the book and the other end on the floor.
Answer» C, d, B, a c, d, a, b c, b, d, a a, b, c, d Answer :B

Discussion

4877.	Which one of the following green house gases is a contributor due to incomplete combustion of coal and petroleum ?
Answer» OXIDES of nitrogen Methane Carbon MONOXIDE Carbon DIOXIDE ANSWER :C

Discussion

4878.	Which of the mirrors is diverging mirror?
Answer» CONCAVE Mirror Convex Mirror Plane Mirror None of these Answer :B

Discussion

4879.	What will you do ? Why ? You are spending more time in internet/mobile games, phone , etc.
Answer» SOLUTION :In life, the time once spent never returns back. We therefore must use our time for studies, EXERCISE or outdoor games and some entertainment . In the free time ,we must also help our PARENTS in house hold work. But if we are spending hours together on SURFING the net without any perfect aim or playing hours together on surfing the net without any perfect aim or playing the compurter or cell PHONE games it is total waste of time. There are many inappropriate sites on the internet, which should not be watched. This causes stress. Continuous use of mobile phone and being hooked to the social mediaslowly becomes an addiction. If these bed habits are creeping in us, we must try to leave the habits by conscious change.

Discussion

4880.	A 120 m long train is moving in a direction with a speed of 20ms^(-1). Another train (130m long) moving with 30ms^(-1) in the opposite directon crosses the first train in a time
Answer» 36 s 30 s 6 s 5 s Solution :Required time = `("TOTAL length of trains")/(v_(1)+v_(2))`, as trains are moving in OPPOSITE directions. = `(120+130)/(20+30)` `=(250)/(50)` =5 sec

Discussion

4881.	What is dispersion ? What happens when light is passed through a glass prism ?
Answer» Solution :The PHENOMENON of splitting of light into its CONSTITUENT colours is known as dispersion of light. When light is passed through a PRISM, light RAYS bend towards its BASE due to double refraction from the faces of the prism. If white light is passed through the prism, its splits into even consituent colours.

Discussion

4882.	Mean value of the acceleration due to gravity is ………………………
Answer» `10.1 MS^(-2)` `8.8 ms^(-2)` `9.8 ms^(-2)` `9.8 ms` SOLUTION :`9.8 ms^(-2)`

Discussion

4883.	(a) "A convex lens can form a magnified erect as well as magnified inverted image of an object placed in front of it." Draw ray diagram to justify this statement statiny the position of the object with respect to the lens in each case. (b) An object of height 4 cm is placed at a distance of 20 cm from a concave lens of focal length 10 cm. Use lens formula to determine the position of the image formed.
Answer» Solution :(a) A convex lens can form a magnified, REAL and inverted image of an object placed in front of it when object is situated somewhere between `F_(1) and 2F_(1)` as shown in FIGURE. On the other hand, a convex lens can form a magnified and erect image of an object when the object is situated between optical centre O and FOCUS point `F_(1)` as shown in figure. (b) As per QUESTION, u = - 20 cm, h = 4 cm and f = - 10 cm Lens formula is `(1)/(v) - (1)/(u) = (1)/(f)` `therefore""(1)/(v) = (1)/(u) + (1)/(f) = (1)/((-20)) + (1)/((-10)) = (-1-2)/(20) = (-3)/(20) rArr v = - (20)/(3) cm = - 6.67 cm`

Discussion

4884.	Amongst iron, silver, nichrome, tungsten, copper, which metal / alloy should be used to make the (i) Heating element of electric geysers (ii) Filament of lncandescent bulbs. An electric iron has rating of 750W, 220V. Calculate: (i) Current required and (ii) Its resistance when it is in use.
Answer» Solution :(i) Heating element - Nichrome (ii) Filament of bulb - Tungsten P = 750 W V= 220 V (i) P =VI` :. I = (P)/(V) = (750)/(220)= 3.4 A` (ii) R = V/I `= (220V)/(3.4A)= 64.5 OMEGA`

Discussion

4885.	Light is a from of energyand it travels in a straight line.
Answer» ANSWER :1

Discussion

4886.	Describe an experiment to illustrate the action of an electric fuse.
Answer» Solution :Safety Fuse or Fuse. Usually the WIRE chosen for electric circuit are such that these allow a certain maximum current to pass through them without excessive heating to pass through them without excessive heating of the circuits. If however, incidentally there is a short-circuiting or over-loading, the current exceeds this maximum permissible value. The wires may get over-heated and CATCH a fire. Sparking at the points of short-circuit may also cause fire. The most important safety fuse or fuse. Fuse is a piece of wire of a material with a low melting POINT. Good fuse wire is always made of pure tin but cheaper variety is made of alloy of tin and copper or tin and lead (63% tin and 37% lead). Fuse is Always Connected to the Live Wire. When current is value more than maximum permissible is passed through the circuit, the fuse wire metls due to excessive heating. THis way the circuit is broken to ensure safety of the circuit. It is due to this fact that the fuse is usually called safety fuse. The thickness, length and material of the fuse wire depends upon the maximum current permitted through the circuit. For proper protection, a fuse of proper value is MUST. Fuse of IMPROPER rating is a curse instead of being a safety device.

Discussion

4887.	Three vessel of equal capacity have gases at the same temperature and pressure. The first vessel contains neon (monoatomic), the second contains chlorine (diatomic), and the third contains uranium hexafluoride (polyatomic). Do the vessels contains equal number of respectice molecules ? Is the root mean square speed of molecules the same in the three cases ? If not, which case is v_(rms) the largest?
Answer» SOLUTION :Three vessels at the same pressure and temperature have same volume and contain equal number of MOLECULES. `V_(RMS)=sqrt((3RT)/(m))`, `V_(rms) prop (1)/(sqrt(m))` rms SPEED will not same, neon has smallest mass therefore rms speed will be largest for neon.

Discussion

4888.	If the tension in the cable supporting an elevator is equal to the weight of elevator, the elevator my be
Answer» going up with increasing SPEED going down with increasing speed going up with UNIFORM speed elevator FALLS FREELY under gravity Solution :Impulse `=int FDT`

Discussion

4889.	Which are the animals from phylum Arthropoda those have shortest and longest life span ?
Answer» SOLUTION :The shortest life span : May FLY - About 24 HOURS . The longest life span : Lobster (Homarus americanus ) - About 100 YEARS .

Discussion

4890.	The sacttering of light rays by the colloidal solution is called Tyndall effect.
Answer» ANSWER :1

Discussion

4891.	A body weight 63 N on the surface of the earth. What is the gravitational force on it due to the earth at a height equal to doubled the radius of the earth?
Answer» Solution :Here `mg=63 N, H=2R` As `(g_h)/(G)=((R )/(R+h))^2= ((R )/(R+R2))= (1/3)^2= (1)/(9)` `g_(h)= (1)/(9)g` `:. ""mg_(h)= (1)/(9)mg=(1)/(9)xx63=7N`.

Discussion

4892.	All elements of an electric circuit are connected in series except:
Answer» voltmeter ammeter rheostat resistor Solution :In an ELECTRIC CIRCUIT all other elements are CONNECTED in series but a voltmeter is connected in PARALLEL.

Discussion

4893.	____________ is ATP factory of the cells.
Answer» MITOCHONDRIA Nucleus Ribosomes Chloroplast ANSWER :A

Discussion

4894.	Addictive person can think rationally.
Answer» SOLUTION :FALSE : ADDICTIVE personh cannot THINK RATIONALLY

Discussion

4895.	Give two practical applications of total internal reflection.
Answer» ANSWER :In medical FIELD - EndoscopeIn field of TELE communication - OPTICAL FIBRE cables

Discussion

4896.	Name the two major components present in the leftover slurry of a biogas plant.
Answer» SOLUTION :NITROGEN and PHOSPHOROUS.

Discussion

4897.	Aqueous solutions of sodium chloride, sodium sulphate and calcium chloride are taken in three separate test tubes. Using aqueous barium chloride how do you identify sodium sulphate?
Answer» Solution :When a solution of sodium sulphate is added to a solution of barium CHLORIDE a white precipitate of barium sulphate will be FORMED immediately. This precipitate is insoluble in dil-Hydrochloric acid and also insoluble in WATER. This type of REACTION is CALLED precipitation reaction as the `BaSO_4`precipitate thus formed is of white colour. `Na_2 SO_4 (aq) + BaCl_2 (aq) to BaSO_4(s) + 2NaCl(aq)` Since, barium sulphate is insoluble in water. So it will precipitate as a solid, whereas the sodium chloride will remain in solution.

Discussion

4898.	Name the river which the following dams are associated . (i)Tehri dam (ii)Sardar Sarovar dam.
Answer» Solution :(i)Tehri dam on the RIVER GANGA. (ii)Sardar SAROVAR dam on the river Narmada.

Discussion

4899.	Addictive person think rationally.
Answer» SOLUTION :False-Addictive PERSON cannot THINK RATIONALLY.

Discussion

4900.	Whiledecidingthe unitfor heat, whichtemperatureintervalis chosen ? Why ?
Answer» Solution :The TEMPERATURE RANGE of `14.5^(@)C` to `15.5^(@)C ` ischosenwhiledecidingthe unitfor HEAT . If weheat 1 KG of WATER by `1^(@)C`in differenttemperaturerangeother than`14.5^(@)C`to `15.5^(@)C`theamountheatrequiredwill beslightly different .

Discussion

Explore topic-wise InterviewSolutions in .

Twp lenses of power +12 D and -2 D are placed in contact. The focal length of the combination is

In the euqation of motion, x=at + bt^(2), the units of a and b are respectively

Write the lens Formula.

The translational kinetic energy of gas molecules for 1 mol of gas is equal to

…………………is the important neurotransmitter released by neurons.

At what common temperature a block of wood metal appear equally cold or hot when touched?

Cnidoblast:

A bob of mass 0.1 kg hung from the ceiling of room by a string 2 m long is oscillating. At its mean position the speed of a bob is 1 ms^(-1). What is the trajectory of the oscillating bob if the string is cut when the bob is (i) At the mean position (ii) At its extreme position.

A piece of wire of resistance R is cut into five equal parts. These parts are thenconnected in parallel. If the equivalent resistance of this combination is R., then the ratio R/(R.) is ………………. .

Rayleigh's scattering is inelastic scattering.

Lead nitrate solution is added to a tes tube containing potassium iodide solution. (a) Write the name and colour of the compound precipitated. (b) Write the balanced chemical equation for the reaction involved. (c ) Name the type of this reaction justifying your answer.

Give an example of a phenomenon where Tyndall effect can be observed.

Effective disaster management makes us well prepared for future. Explain why it is said like that.

Lactobacilli in Yoghurt industry:

Do all vibrating bodies necessarily produce sound?

The numerical value of density in SI is n times its value in cgs system. The value of n is

Name two main fossil fuels.

List two methods of producing magnetic fields.

Which phenomena can you study using a glass prisms ?

In the equation ""_6C^(14) to ""_7N^(14) +""_(-1)e^(0) which decay of radioactive carbon-14 results in the new nitrogen-14 atom ?

Free fall

The refractive index of ice is …………… .

Derive an expression for the effective resistance when three resistors are connected in (i) series (ii) parallel.

Why do the farmers fill their fields with water in winter.

A free charged particles moves through a magnetic field the particle may undergo a change in :

Which one of the following green house gases is a contributor due to incomplete combustion of coal and petroleum ?

Which of the mirrors is diverging mirror?

What will you do ? Why ? You are spending more time in internet/mobile games, phone , etc.

A 120 m long train is moving in a direction with a speed of 20ms^(-1). Another train (130m long) moving with 30ms^(-1) in the opposite directon crosses the first train in a time

What is dispersion ? What happens when light is passed through a glass prism ?

Mean value of the acceleration due to gravity is ………………………

Amongst iron, silver, nichrome, tungsten, copper, which metal / alloy should be used to make the (i) Heating element of electric geysers (ii) Filament of lncandescent bulbs. An electric iron has rating of 750W, 220V. Calculate: (i) Current required and (ii) Its resistance when it is in use.

Light is a from of energyand it travels in a straight line.

Describe an experiment to illustrate the action of an electric fuse.

If the tension in the cable supporting an elevator is equal to the weight of elevator, the elevator my be

Which are the animals from phylum Arthropoda those have shortest and longest life span ?

The sacttering of light rays by the colloidal solution is called Tyndall effect.

A body weight 63 N on the surface of the earth. What is the gravitational force on it due to the earth at a height equal to doubled the radius of the earth?

All elements of an electric circuit are connected in series except:

____________ is ATP factory of the cells.

Addictive person can think rationally.

Give two practical applications of total internal reflection.

Name the two major components present in the leftover slurry of a biogas plant.

Aqueous solutions of sodium chloride, sodium sulphate and calcium chloride are taken in three separate test tubes. Using aqueous barium chloride how do you identify sodium sulphate?

Name the river which the following dams are associated . (i)Tehri dam (ii)Sardar Sarovar dam.

Addictive person think rationally.

Whiledecidingthe unitfor heat, whichtemperatureintervalis chosen ? Why ?