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5001.

3. Phases of the moon occur because(a) we can see only that part of the moon which reflects light(b)(c)(d)towards us.our distance from the moon keeps changing.the shadow of the Earth covers only a part of the moon's surface.the thickness of the moon's atmosphere is not constant.

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(a)we can see only that part of the moon which reflects light towards us

5002.

•In the figure a hemispherical bowl of radius Ris shown. Electric field of intensity E ispresent perpendicular to the circular cross section of the hemisphere. The electricflux through the hemisphere is(A)(B) ERR(C) E2R(D) E3 R

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B ) is correct answer

5003.

n]S4. In the arrangement shown in Fig. 3(a),50that tension in the string between masses show2 andm +m2 +m3FIGURE 3(a).501T1 lam1m2m3

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5004.

6. A charge of magnitude Q is divided into two parts9 and (Q - 9) such that the two parts exertmaximum force on each other. Calculate the ratioa.[Ans. 2]

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yes above 2nd answer is right

5005.

120D 1.0X IUC16. A charge Q is to be divided into two partssuch that the force between them ismaximum. They should be divided as

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let parts are sepereted at a distance of d

so repulsion force F= k q(Q-q)/d^2

here Q and d are constant so for maximum force differentiate the force w.r.t q

dF/dq = k/d^2[Q -2q]

for maximum force dF/dq=0

Q-2q=0

Q/q =2

5006.

2 Martsesoube申Ofon Valde-of

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5007.

what is Polaroid?

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Ans :- Material in thin plastic sheets that produces a high degree of plane polarization in light passing through it.

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thnx

5008.

11. (i) Light passes through two polaroids P1 and P2 with axis of P2 making on angle θ is theintensity of emergent light zero?

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At 90°, the intensity of the emergent light is zero.

5009.

(ii) A third Polaroid is placed between Pl and P2 with its pass axis making an angle β withthe passes axis of P1 and P2 value of β for which the intensity of light emerging from P2 islo/8, where lo is the intensity of light on the Polaroid P.

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5010.

A light string fixed atone end to a clamp onround passes over atixed pulley and hangsat the other side, Itmakes an angle of 30withthe ground. A monkey of mass 5 kg climbs up the ropeThe clamp can tolerate a vertical force of 40n only, Themaximum acceleration in upward direction with whichthe monkey can elimb safely is (neglect friction andtake g 10 m/u)30

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5011.

Define the unit of force using the second law of motion. A force of 5N produces an acceleration of8m/s2 on a mass m1 and an acceleration of 24 m/s on a mass m2. What acceleration would the sameforce provide if both the masses are tied together?

Answer»

thanks, from where did you got the answer

5012.

10. Two polaroids Pi and P2 are placed with their pass axes perpendicular to each otherUnpolarized light of intensity lo is incident on P1. A third Polaroid P3 is kept in between Piand P2 such that its pass axis makes an angle of 30 with that of Pi. Determine the intensityof light transmitted through Pi, P2 and Ps.

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5013.

IL115 VIU.A positive charge q is placed in front of a conductingsolid cube at a distance d from its centre. Find theelectric field at the centre of the cube due to the chargesappearing on its surface.

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5014.

Two particles A and B having charges of +2.00 x10°C and of -4.00 x 106C respectively are heldfixed at a separation of 20.0 cm. Locate the point(s)on the line AB where the electric field is zero.bobbendolo

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5015.

Two particles A and B having charges of +2.00 *10*C and of -4.00 x 10-C respectively are heldfixed at a separation of 20.0 cm. Locate the point(s)on the line AB where the electric field is zero.

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5016.

Two fixed charges A and B of 5 pC each are separated by adistance of 6 m. C is the mid point of the line joining A andB. A charge 'Q of -5C is shot perpendicular to the linejoining A and B through C with a kinetic energy of 0.06 J.The charge 'Q comes to rest at a point D. The distance CD[KCET 2012]IS

Answer»

the charge q = - 5μC starts with a KE of 0.06 J from point C and stops at point d.

Initial total energy of the charge q = KE + PE = 0.06 + 9*10⁹ * 5 *10⁻⁶ * (-5 *10⁻⁶)/3 + 9*10⁹ * 5*10⁻⁶*(-5*10⁻⁶)/3 J = 0.06 - 0.075 - 0.075 J = - 0.09 J

Let ad = bd = x m

Final energy = PE (as KE = 0) = - 2 * 9*10⁹ * 5*10⁻⁶ * 5 * 10⁻⁶ /x J = - 0.450/x J

Hence, using Energy conservation we get: 0.450/x = 0.09 x = 5 mcd =√(x² - 3²) = 4 m

5017.

Two small balls having equal positivecharge Q on each are suspended by twoinsulating strings at equal length L meter,from a hook fixed to a stand. The wholeset up is taken in a satellite into space wherethere is no gravity. Then the angle a betweentwo strings and tension in each string is-

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5018.

0.50.19Equivalent resistance between the points A and B isfin )in10

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5019.

the length of inclined plane at 30°is 20 m and sphere of mass 5 kg start rolling from the rest from the top of the plane if there is 20% loss of kinetic energy due to friction etc. then calculate the velocity of the sphere at the bottom of the plane

Answer»

The change in kinetic energy when the ball reaches the bottom of the plane is 500J loss due to friction =100J (20%of 500J )net change in kinetic energy=400J 1/2×mass of ball×(velocity at base of the plane^2)-1/2×mass of the ball×(velocity at the top of the plane^2)=400J1/2×mass of the ball ×velocity at the base of the plane=400J (because velocity at the top of the plane is 0)1/2×5×(velocity at base ^2)=400Jvelocity at base =4 (root10)

5020.

)The taxi charges in a city consist of a fixed charge together with the charge for the105 and for adistance covered. For a distance of 10 km, the charge paid isjourney of 15 km, the charge paid is 155. What are the fixed charges and thecharge per km? How mach does a person have to pay for travelling a distance of25 km?9

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Letthe fixed chargefor taxi= Rs x

Andvariable cost per Km= Rs y

Total cost= fixed charge + variable charge

Given that for a distance of 10 km, the charge paid is Rs 105

x + 10 y= 105… (1)

x= 105 – 10 y

Given that for a journey of 15 km, the charge paid is Rs 155

x + 15 y= 155

Plug the value of x we get

105 – 10 y + 15 y= 155

5y= 155 – 105

5y= 50

Divide by 5we get

y= 50 / 5= 10

Plug this value in equation (1) we get

x= 105 – 10 * 10

x= 5

People have to pay for traveling a distance of 25 km

= x + 25 y

= 5 + 25*10

= 5 + 250

=255Please like the solution 👍 ✔️

5021.

2 The electrostatic force on a small sphere of charge 0.4 pC due toanother smaall sphere of ehange-0,8 pC In air 0.2 N. (a) What,isthe distance between the two spheres? What is the force on thesecond sphere due to the first?

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5022.

57. The equilibrium constant (K) for the reactionPC/5(g) → PC,(g) + C12(g) is 16. If the volume of thecontainer is reduced to one half its original volume, thevalue of K for the reaction at the same temperature will be(a) 32(c) 16(b) 64(d) 4

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PCl5dissociates as:PCl5⇌ PCl3Cl2If p is the degree of dissociation at certain temperature under atmospheric pressure, thenInitial concentration:PCl5= 1PCl3= 0Cl2= 0At Equilibrium:PCl5= 1 – pPCl3= pCl2= pTotal number of moles at equilibrium = 1 – p + p + p = 1 + pPartial pressures of PCl5, PCl3and Cl2will be:p (PCl3) = p p / 1 + pp (Cl2) = p p / 1 + pp (PCl5) = (1 – p) p / 1 + pKp= p (PCl3) X p (Cl2) / p (PCl5)Kp=[(p p / 1 + p) X (p p / 1 + p)]/[(1 – p) p / (1 + p)]= p^2p / (1 – p)^2

5023.

Q. 13. What is fruit ?

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Ans :- Fruits are the means by which angiosperms disseminate seeds. In common language usage, "fruit" normally means the fleshy seed-associated structures of a plant that are sweet or sour, and edible in the raw state, such as apples, bananas, grapes, lemons, oranges, and strawberries.

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5024.

why are standard units used in measurememts

Answer»

Standard unitsareused in measurementbecause otherunitssuch as hand span are not appropriate because each person has different height.

5025.

1. Why are standard units used in measurements?

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5026.

OT-ANSWER QUESTIONS: Answer in a senterC. SHORT-ANSW1. Why are standard unVhy are standard units used in measurements?

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because another units are used in measurement are appropriate from person to person . so standard unit are used in measurement

5027.

Define mechanical equivalent of heat. Give its values in SI and CGS system.

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the mechanical equivalent of heat states that motion and heat are mutually interchangeable and that in every case, a given amount of work would generate the same amount of heat, provided the work done is totally converted to heat energy.

W=JH

J=W/H

W is the mechanical work which is equivalent to heat energy H. Now in SI unit both work and heat are measured in Joules. So mechanical equivalent of heat J= Joule/Joule = 1 (dimensionless)

In cgs units, heat is measured in calorie while work in erg. Now 1 calorie = 41800000 ergs approximately. So J= 41800000 ergs/calorie.

5028.

8] The density of mercury is 13,595 kg/m3. Find its density in CGS system.

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5029.

The size of a bacteria is 1 μ. Find the number ofbacteria in 1 m length.

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If 0.000001 m space is occupied by 1 bacterium then 1m will be occupied by 1/0.000001= 1000000 bacteria

5030.

1. If the magnification of a body of size 1 m is 2, what is the size of the image

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5031.

4,¡s it possible to have value of absolute refractive index less than 1 . If not why?OR

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No, The speed of light in vacuum is 2.998×10^8 m/s.

Speed of light is not possible to be more than the speed of light in vacuum. So, the minimum refractive index is 1.

5032.

What is absolute refractive index

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5033.

a. If the speed of light in a medium is1.5 x 10^8 m/s, what is the absoluterefractive index of the medium?

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5034.

ii. If in a medium, the speed of light is 1.5 x 108 m/s, how much will the absolute refractiveindex of that medium be?

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V= 1.5×10 ^8m/s.

C= 3×10^8 m/s.

To find: n

solution: c/v.

n= 3×10^8 /1.5×10^8

n = 2.

5035.

1. A park, in the shape of a quadrilateral ABCD, has Z C = 90°, AB = 9 m, BC = 12 m,CD = 5 m and AD = 8 m. How much area does it occupy?

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Given a quadrilateral ABCD in which ∠C = 90º, AB = 9 m, BC = 12 m, CD = 5 m & AD = 8 m.

ER. RAVI KUMAR ROY

Join the diagonal BD which divides quadrilateral ABCD in two triangles i.e ∆BCD & ∆ABD.

In ΔBCD,By applying Pythagoras Theorem

BD²=BC² +CD²

BD²= 12²+ 5²= 144+25

BD²= 169BD = √169= 13m

∆BCD is a right angled triangle.

Area of ΔBCD = 1/2 ×base× height

=1/2× 5 × 12= 30 m²

For ∆ABD,Let a= 9m, b= 8m, c=13m

Now,Semi perimeter of ΔABD,(s) = (a+b+c) /2

s=(8 + 9 + 13)/2 m= 30/2 m = 15 m

s = 15m

Using heron’s formula,Area of ΔABD = √s (s-a) (s-b) (s-c)

= √15(15 – 9) (15 – 9) (15 – 13)

= √15 × 6 × 7× 2 =√5×3×3×2×7×2=3×2√35= 6√35= 6× 5.92

[ √6= 5.92..]= 35.52m² (approx)

Area of quadrilateral ABCD = Area of ΔBCD + Area of ΔABD = 30+ 35.5= 65.5 m²

Hence, area of the park is 65.5m²

5036.

who does sound propagate? does sound travel in vacam? why?

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Sound does not travel in vaccum because it needs a medium to travel.

5037.

6.12.The equation of a simple harmonic progressive waveis,y = 0.02 sin--(360 t-x15If the distances are in meters and time in secondDetermine the period, wavelength andspeed of thewave.

Answer»

This is a similar question-

5038.

harmonic prugIESSIVE(4) Explain the reflection of sound waves fromcurved surface.PROBLEMS FO(1) The equation of a simple harmonic progressivewave is given by y = 4 sin ut (0- cm.Find the displacement and velocity of theparticle at a distance of 50 cm from the originand at the instant 0.1 second (all quantities are inc.g.s. units)(Ans : Displacement = 3.464 cm,Velocity of the particle = 3.14 m/s)(2) The frequency of a tuning fork in 256

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Displacement of particle , y = 4sinπ(t/0.02 - x/75) here t = 0.1 sec and x = 50cm

so, y = 4sinπ(0.1/0.02 - 50/75)

y = 4sinπ(5 - 2/3)

y = 4sinπ(13/3) = 4sin(13π/3)

y = 4sin(4π + π/3) = 4sinπ/3 = 4 × √3/2

y = 2√3 = 2 × 1.732 = 3.464 cm

y = 4sinπ(t/0.02 - x/75)

differentiate with respect to t,

dy/dt = (4/0.02)πcosπ(t/0.02 - x/75)

v = 200πcosπ(t/0.02 - x/75)

at t = 0.1 sec and x = 50cm

v = 200πcosπ(0.1/0.02 - 50/75) = 200πcos(13π/3)

v = 200πcos(4π + π/3) = 200πcosπ/3

v = 200π × 1/2 = 100π = 314 cm/s or 3.14 m/s

5039.

\begin{array} { l } { \text { (7) Write the equation of a simple harmonic progress- } } \\ { \text { ive wave of amplitude } 0.05 \mathrm { m } \text { and period } 0.04 \text { s } } \\ { \text { travelling along the positive } x \text { -axis with a velocity } } \\ { \text { of } 12.5 \mathrm { m } / \mathrm { s } . } \end{array}.

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1

2

5040.

7. For the travelling harmonic wavey(x, t) = 2.0 cos2π (10t - 0.0080x + 0.35) where x and y are in cm,calculate the phase difference between oscillatory motion of two points31separated by a distance of (a) 4 m (b) 0.5 m (c) (d

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5041.

(44) Transverse progressive wave.

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Waves move energy from one place to another. In a progressive wave the wave front moves through the medium. There are two types of waves, transverse and longitudinal. Transverse waves are waves where the displacement of the particles in the medium is perpendicular to the direction the wave is travelling in.

5042.

What is progressive wave ?

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A progressive wave is a wave where continuous energy transfer takes place between the crest and trough (transverse wave) or between rarefactions and compressions (long waves). These waves are associated with 2 trigonometric functions in terms of space and time

5043.

ą2. Given two vectors A 4+ 3 and B i-2jl. Find the magnitude of each vector.Il. Write an expression for the vector difference A B using these vectors.IlI. Find the magnitude and directions of the vector difference A-Btor t3+1+2k on the x-y plane.

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5044.

Q.if the sum of two unit vectors is a unitvectorthen find the magnitude of theirdifference?

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5045.

which the anhould ve r teainrelt aiovetatock SO-aaltof.venate-speed-tokulhPon the sp

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90km/hr

Solutions

5046.

Can any object have mechanical energy even ifits momentum is zero? Explain.

Answer»

An objectthat possessesmechanical energyis able todowork.

In fact,mechanical energyis often defined as the ability todowork.

Any objectthat possessesmechanical energy- whether it is in the form of potential energyor kineticenergy- is able todowork.

Momentumis the product of mass and velocity of a body, for a body mass never bezerobut velocitycanbezero ifa body is at rest, Soifa body is at restits momentum is zerobutif it isin rest at a height it possesses gravitational potentialenergyhencemechanical energy.

Momentumistheproduct of mass and velocity of a body, for a body mass never bezerobut velocitycanbezero ifa body is at rest, Soifa body is at restits momentum is zerobutif it isin rest at a height it possesses gravitational potentialenergyhencemechanical energy.

5047.

I. Is it possible that a force is acting on a body but the work done is zero.Explain by givmg an example.Yollot.

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5048.

4. Under what condition the three vectors give zeroresultant?7

Answer»

When all the three vectors are insameplane and forms a triangle and sum of two sides of the triangle is greater than the third side or the sum of any two vectors isequalto third one then all the three vectors arecollinearwill produce their resultant zero.

5049.

An object will continue moving uniformly when(a) The resultant force on it is increasingcontinuously(b) the resultant force is at right angles to itsrotation(c) The resultant force on it is zero(d) The resultant force on it begins to decreasebufo 11c food

Answer»

Motion is caused due to force. So an object moving at a uniform rate will keep moving till the force is applied on the object. Once the force is zero, there will be no motion and so the object will stop moving uniformly.

5050.

(d) Can the resultant of 2 vectors be zero

Answer»

Yes,two vectorsof equal magnitude that are pointing in opposite directionswillsum tozero.Two vectorsof unequal magnitudecannever sum tozero. If they point along the same line, since their magnitudes are different, the sumwillnot bezero.

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