50278 + Interview Questions in Physics

1.	A boy is rotating in a circular motion, a stone of mass 500 gm by using a string of50 cm length with a speed of 10 cm/s. What will be the work done by the force applied by the boy?
Answer» A boy is rotating in a circular motion, a stone of mass 500 gm by using a string of50 cm length with a speed of 10 cm/s. What will be the work done by the force applied by the boy?

Discussion

2.	How many significant figures are their in1. 2 kg2. 2
Answer» How many significant figures are their in 1. 2 kg 2. 2

Discussion

3.	The frequency of oscillation of current in the inductor is
Answer» The frequency of oscillation of current in the inductor is

Discussion

4.	A bi-convex thin lens is prepared from glass (μ=1.5), the two bounding surfaces having equal radii of 25 cm each. One of the surface is silvered from outside. Where should an object be placed before this lens such that the image is formed at the object position itself?
Answer» A bi-convex thin lens is prepared from glass $(μ = 1.5)$ , the two bounding surfaces having equal radii of $25 cm$ each. One of the surface is silvered from outside. Where should an object be placed before this lens such that the image is formed at the object position itself?

Discussion

5.	A body moving with uniform retardation cover 3km before its speed is reduced to half of its initial value. It comes to rest in another distance of
Answer» A body moving with uniform retardation cover 3km before its speed is reduced to half of its initial value. It comes to rest in another distance of

Discussion

6.	The internal energy of a monoatomic ideal gas is 1.5nRT. One mole of helium is kept in a cylinder of cross-section 8.5 cm2. The cylinder is closed by a light frictionless piston. The gas is heated slowly in a process during which a total of 42 J heat is given to the gas. The temperature rises through 2∘C. The distance moved by the piston is given as a×10b m in scientific notation. Find the value of a+b. Here, a,b are integers [Take R=253 in SIunit,atmospheric pressure =100kPa]
Answer» The internal energy of a monoatomic ideal gas is $1.5 n R T$ . One mole of helium is kept in a cylinder of cross-section $8.5 {cm}^{2}$ . The cylinder is closed by a light frictionless piston. The gas is heated slowly in a process during which a total of $42 J$ heat is given to the gas. The temperature rises through $2^{\circ} C$ . The distance moved by the piston is given as $a \times 10^{b} m$ in scientific notation. Find the value of $a + b$ . Here, $a, b$ are integers [Take $R = \frac{25}{3}$ in $S I u n i t$ ,atmospheric pressure = $100 kPa$ ]

Discussion

7.	A wheel starting from rest is uniformly accelerated at 4 rad/s2 for 10 seconds . It is allowed to rotate uniformly for the next 10 seconds and is finally brought to rest in the next 10 seconds. Find the total angle rotated by the wheel.
Answer» A wheel starting from rest is uniformly accelerated at 4 rad/s $^{2}$ for 10 seconds . It is allowed to rotate uniformly for the next 10 seconds and is finally brought to rest in the next 10 seconds. Find the total angle rotated by the wheel.

Discussion

8.	If speed of sound in a gas at 127^° C is 400 m/s, then time taken by sound pulse to travel a dis†an ce 2 km between two points in gas column if temperature between the points vary linearly from 127^° C to 627^° C is
Answer» If speed of sound in a gas at 127^° C is 400 m/s, then time taken by sound pulse to travel a dis†an ce 2 km between two points in gas column if temperature between the points vary linearly from 127^° C to 627^° C is

Discussion

9.	The following figure shows the displacement versus time graph for two particles A and B executing simple harmonic motions. The ratio of their maximum velocities (respectively) is
Answer» The following figure shows the displacement versus time graph for two particles $A$ and $B$ executing simple harmonic motions. The ratio of their maximum velocities (respectively) is

Discussion

10.	A wire (fixed at both ends) of length l having tension T and radius r vibrates with natural frequency f. Another wire of same metal with length 2l having tension 2T and radius 2r will vibrate with natural frequency
Answer» A wire (fixed at both ends) of length $l$ having tension $T$ and radius $r$ vibrates with natural frequency $f$ . Another wire of same metal with length $2 l$ having tension $2 T$ and radius $2 r$ will vibrate with natural frequency

Discussion

11.	A resistance of 20 ohms is connected to a source of an alternating potential V=220 sin(100 πt). The time taken by the current to change from its peak value to r.m.s value is
Answer» A resistance of 20 ohms is connected to a source of an alternating potential $V = 220 s i n (100 π t)$ . The time taken by the current to change from its peak value to r.m.s value is

Discussion

12.	A photon of energy 8 eV is incident on a metal surface of threshold frequency 1.6×1015Hz, then the maximum kinetic energy of photoelectrons emitted is (h=6.6×10−34Js)
Answer» A photon of energy 8 eV is incident on a metal surface of threshold frequency $1.6 \times 10^{15} H z$ , then the maximum kinetic energy of photoelectrons emitted is $(h = 6.6 \times 10^{- 34} J s)$

Discussion

13.	If the coefficient of friction between an insect and bowl is μ and the radius of the bowl is R. Then the maximum height to which the insect can crawl in the bowl is
Answer» If the coefficient of friction between an insect and bowl is $μ$ and the radius of the bowl is $R$ . Then the maximum height to which the insect can crawl in the bowl is

Discussion

14.	Does raincoat increase angle of contact ? If yes then how come it increases surface tension and prevents penetration of water?
Answer» Does raincoat increase angle of contact ? If yes then how come it increases surface tension and prevents penetration of water?

Discussion

15.	consider the arrangement shown in figure (17-E4). The distance D is large compared to the separation d between the slits. (a) Find the minimum value of d so that there is a dark fringe at O. (b) suppose d has this value. Find the distance x at which the next pright fringe is formed. (c) Find thd fringe- width.
Answer» consider the arrangement shown in figure (17-E4). The distance D is large compared to the separation d between the slits. (a) Find the minimum value of d so that there is a dark fringe at O. (b) suppose d has this value. Find the distance x at which the next pright fringe is formed. (c) Find thd fringe- width.

Discussion

16.	In Second class Lever _______is in the middle between the _________and the __________
Answer» In Second class Lever _______is in the middle between the _________and the __________

Discussion

17.	Three bars of copper ( modulus of elasticity Y)having length L and 2L and 3 l and area of cross section A, 2A and 3A are joined rigidly end-to-end compound rod subjected to a stretching force f find the net modulus of elasticity of the system of wires.
Answer» Three bars of copper ( modulus of elasticity Y)having length L and 2L and 3 l and area of cross section A, 2A and 3A are joined rigidly end-to-end compound rod subjected to a stretching force f find the net modulus of elasticity of the system of wires.

Discussion

18.	Area of cross section of large tank is 0.5 m² . it has an opening near the bottom having area of cross section 1 cm² a load of 20 kg is applied on the water at the top. find velocity of water coming out of the opening at the time when height of water level is 50 cm above the bottom?
Answer» Area of cross section of large tank is 0.5 m² . it has an opening near the bottom having area of cross section 1 cm² a load of 20 kg is applied on the water at the top. find velocity of water coming out of the opening at the time when height of water level is 50 cm above the bottom?

Discussion

19.	A spring of spring constant 5 x10^3 N/m is stretched initially by 4 cm from the unstretched position. Then work required to stretch it further byanother 6 cm is(1) 5 J(3) 10 J(2) 2.5 J(4) 20 J
Answer» A spring of spring constant 5 x10^3 N/m is stretched initially by 4 cm from the unstretched position. Then work required to stretch it further byanother 6 cm is(1) 5 J(3) 10 J(2) 2.5 J(4) 20 J

Discussion

20.	57.A tuning fork gives 4 beats with 50 cm length of sonometer wire. If the length of the wire is shortened by 1 cm, the number of beats is still the same. The frequency of the fork is ?
Answer» 57.A tuning fork gives 4 beats with 50 cm length of sonometer wire. If the length of the wire is shortened by 1 cm, the number of beats is still the same. The frequency of the fork is ?

Discussion

21.	According to Joule's law of heating, the heat produced is given by H=I2 Rt, where I is current, R is resistance and t is the time. If the errors in the measurement of I,R and t are 3 %, 4 % and 6 % respectively, then the error in measurement of H is:
Answer» According to Joule's law of heating, the heat produced is given by $H = I^{2} R t,$ where $I$ is current, $R$ is resistance and $t$ is the time. If the errors in the measurement of $I, R$ and $t$ are $3 %$ , $4 %$ and $6 %$ respectively, then the error in measurement of $H$ is:

Discussion

22.	If velocity of a particle moving along a straight line changes sinusoidally with time as shown in given graph. The average speed over time interval t=0 to t=2(2n−1) second, n being any positive interget, is xπ m/s. Value of x is (Answer upto 2 decimal digits)
Answer» If velocity of a particle moving along a straight line changes sinusoidally with time as shown in given graph. The average speed over time interval $t = 0$ to $t = 2 (2 n - 1)$ second, n being any positive interget, is $\frac{x}{π} m / s$ . Value of $x$ is (Answer upto 2 decimal digits)

Discussion

23.	The terminal velocity of a raindrop of radius 0.3 mm falling through the air of viscosity 1.8×10−5 Ns/m2 is equal to (Consider density of raindrop as 103kg/m3,acceleration due to gravity g=9.8m/s2and Neglect density of air)
Answer» The terminal velocity of a raindrop of radius $0.3 m m$ falling through the air of viscosity $1.8 \times 10^{- 5} N s / m^{2}$ is equal to $($ Consider density of raindrop as $10^{3} k g / m^{3},$ acceleration due to gravity $g = 9.8 m / s^{2}$ and Neglect density of air $)$

Discussion

24.	Prove that:(i) tan 4π-cos3π2-sin5π6cos2π3=14(ii) sin13π3sin8π3+cos2π3sin5π6=12(iii) sin 13π3sin2π3+cos4π3sin13π6=12(iv) sin10π3cos13π6+cos8π3sin5π6=-1(v) tan5π4cot9π4+tan17π4cot15π4=0
Answer» Prove that: (i) $\tan 4 π - \cos \frac{3 π}{2} - \sin \frac{5 π}{6} \cos \frac{2 π}{3} = \frac{1}{4}$ (ii) $\sin \frac{13 π}{3} \sin \frac{8 π}{3} + \cos \frac{2 π}{3} \sin \frac{5 π}{6} = \frac{1}{2}$ (iii) $\sin \frac{13 π}{3} \sin \frac{2 π}{3} + \cos \frac{4 π}{3} \sin \frac{13 π}{6} = \frac{1}{2}$ (iv) $\sin \frac{10 π}{3} \cos \frac{13 π}{6} + \cos \frac{8 π}{3} \sin \frac{5 π}{6} = - 1$ (v) $\tan \frac{5 π}{4} \cot \frac{9 π}{4} + \tan \frac{17 π}{4} \cot \frac{15 π}{4} = 0$

Discussion

25.	Two particles A and B are moving with uniform velocities as shown in the figure given below at t=0. Find out the shortest distance between the two particles.
Answer» Two particles $A$ and $B$ are moving with uniform velocities as shown in the figure given below at $t = 0$ . Find out the shortest distance between the two particles.

Discussion

26.	An α particle is accelerated through a potential difference of V volts. The de Broglie's wavelength associated with it is:
Answer» An $α$ particle is accelerated through a potential difference of $V v o l t s$ . The de Broglie's wavelength associated with it is:

Discussion

27.	A conducting rod AB of mass 100 gm and length 10 cm is placed on two rails as shown. The rod carries a current of 20 A and there is a uniform magnetic field of 1.5 T in the surrounding space. What will be the speed of the rod as it travels through 50 cm along the rails, if it starts from rest. Take μ=0.5 between rails and rod and g=10 m/s2.
Answer» A conducting rod $AB$ of mass $100 gm$ and length $10 cm$ is placed on two rails as shown. The rod carries a current of $20 A$ and there is a uniform magnetic field of $1.5 T$ in the surrounding space. What will be the speed of the rod as it travels through $50 cm$ along the rails, if it starts from rest. Take $μ = 0.5$ between rails and rod and $g = 10 {m/s}^{2}$ .

Discussion

28.	Consider the circuit given below:The value of input resistance Rin is _____102.38
Answer» Consider the circuit given below: The value of input resistance $R_{i n}$ is _____ 102.38

Discussion

29.	A cart of mass 50 kg is moving on a straight track with a speed of 12 m/s. A mass of 10 kg is gently put into the cart. What will be the velocity of the cart after this?
Answer» A cart of mass $50 kg$ is moving on a straight track with a speed of $12 m/s$ . A mass of $10 kg$ is gently put into the cart. What will be the velocity of the cart after this?

Discussion

30.	State any two laws of simple pendulu
Answer» State any two laws of simple pendulu

Discussion

31.	A particle is moving with a velocity →v=k(y^i+x^j), where k is a constant. The general equation for its path is:
Answer» A particle is moving with a velocity $\to v = k (y^i + x^j)$ , where $k$ is a constant. The general equation for its path is:

Discussion

32.	There is a current of 20 A in a wire of cross-sectional area 0.01 cm2. If number of free electrons per cubic metre is 1029, then the drift velocity will be
Answer» There is a current of $20 A$ in a wire of cross-sectional area $0.01 {cm}^{2}$ . If number of free electrons per cubic metre is $10^{29}$ , then the drift velocity will be

Discussion

33.	A particle is projected from the ground. If the equation of the trajectory is y = x - x22 , then the time of flight is
Answer» A particle is projected from the ground. If the equation of the trajectory is y = x - $\frac{x^{2}}{2}$ , then the time of flight is

Discussion

34.	A small disc is set rolling with a speed v on the horizontal part of the track of the previous problem from right to left. To what height will it climb up the curved part ?
Answer» A small disc is set rolling with a speed v on the horizontal part of the track of the previous problem from right to left. To what height will it climb up the curved part ?

Discussion

35.	Constant power P is supplied to a particle having mass m, initially at rest. Choose correct graph between distance covered (s) and time taken (t).
Answer» Constant power $P$ is supplied to a particle having mass $m$ , initially at rest. Choose correct graph between distance covered ( $s$ ) and time taken ( $t$ ).

Discussion

36.	Classically, anelectron can be in any orbit around the nucleus of an atom. Then whatdetermines the typical atomic size? Why is an atom not, say, thousandtimes bigger than its typical size? The question had greatly puzzledBohr before he arrived at his famous model of the atom that you havelearnt in the text. To simulate what he might well have done beforehis discovery, let us play as follows with the basic constants ofnature and see if we can get a quantity with the dimensions of lengththat is roughly equal to the known size of an atom (~ 10−10m).(a) Construct a quantity with the dimensions of length fromthe fundamental constants e, me, andc. Determine its numerical value.(b) You will find that the length obtained in (a) is manyorders of magnitude smaller than the atomic dimensions. Further, itinvolves c. But energies of atoms are mostly innon-relativistic domain where c is not expected to play anyrole. This is what may have suggested Bohr to discard c andlook for ‘something else’ to get the right atomic size.Now, the Planck’s constant h had already made itsappearance elsewhere. Bohr’s great insight lay in recognisingthat h, me, and e will yieldthe right atomic size. Construct a quantity with the dimension oflength from h, me, and e andconfirm that its numerical value has indeed the correct order ofmagnitude.
Answer» Classically, an electron can be in any orbit around the nucleus of an atom. Then what determines the typical atomic size? Why is an atom not, say, thousand times bigger than its typical size? The question had greatly puzzled Bohr before he arrived at his famous model of the atom that you have learnt in the text. To simulate what he might well have done before his discovery, let us play as follows with the basic constants of nature and see if we can get a quantity with the dimensions of length that is roughly equal to the known size of an atom (~ 10⁻¹⁰m). (a) Construct a quantity with the dimensions of length from the fundamental constants e, m_e, and c. Determine its numerical value. (b) You will find that the length obtained in (a) is many orders of magnitude smaller than the atomic dimensions. Further, it involves c. But energies of atoms are mostly in non-relativistic domain where c is not expected to play any role. This is what may have suggested Bohr to discard c and look for ‘something else’ to get the right atomic size. Now, the Planck’s constant h had already made its appearance elsewhere. Bohr’s great insight lay in recognising that h, m_e, and e will yield the right atomic size. Construct a quantity with the dimension of length from h, m_e, and e and confirm that its numerical value has indeed the correct order of magnitude.

36.

Classically, anelectron can be in any orbit around the nucleus of an atom. Then whatdetermines the typical atomic size? Why is an atom not, say, thousandtimes bigger than its typical size? The question had greatly puzzledBohr before he arrived at his famous model of the atom that you havelearnt in the text. To simulate what he might well have done beforehis discovery, let us play as follows with the basic constants ofnature and see if we can get a quantity with the dimensions of lengththat is roughly equal to the known size of an atom (~ 10−10m).(a) Construct a quantity with the dimensions of length fromthe fundamental constants e, me, andc. Determine its numerical value.(b) You will find that the length obtained in (a) is manyorders of magnitude smaller than the atomic dimensions. Further, itinvolves c. But energies of atoms are mostly innon-relativistic domain where c is not expected to play anyrole. This is what may have suggested Bohr to discard c andlook for ‘something else’ to get the right atomic size.Now, the Planck’s constant h had already made itsappearance elsewhere. Bohr’s great insight lay in recognisingthat h, me, and e will yieldthe right atomic size. Construct a quantity with the dimension oflength from h, me, and e andconfirm that its numerical value has indeed the correct order ofmagnitude.

Answer»

Classically, an
electron can be in any orbit around the nucleus of an atom. Then what
determines the typical atomic size? Why is an atom not, say, thousand
times bigger than its typical size? The question had greatly puzzled
Bohr before he arrived at his famous model of the atom that you have
learnt in the text. To simulate what he might well have done before
his discovery, let us play as follows with the basic constants of
nature and see if we can get a quantity with the dimensions of length
that is roughly equal to the known size of an atom (~ 10⁻¹⁰m).

(a) Construct a quantity with the dimensions of length from
the fundamental constants e, m_e, and
c. Determine its numerical value.

(b) You will find that the length obtained in (a) is many
orders of magnitude smaller than the atomic dimensions. Further, it
involves c. But energies of atoms are mostly in
non-relativistic domain where c is not expected to play any
role. This is what may have suggested Bohr to discard c and
look for ‘something else’ to get the right atomic size.
Now, the Planck’s constant h had already made its
appearance elsewhere. Bohr’s great insight lay in recognising
that h, m_e, and e will yield
the right atomic size. Construct a quantity with the dimension of
length from h, m_e, and e and
confirm that its numerical value has indeed the correct order of
magnitude.

Discussion

37.	Consider the circuit shown in the figure below:If the three bit input to the circuit is (X2X1X0)=101, then the decimal equivalent of the corresponding output of the circuit (Y2Y1Y0) will be equal to ____3
Answer» Consider the circuit shown in the figure below: If the three bit input to the circuit is $(X_{2} X_{1} X_{0}) = 101$ , then the decimal equivalent of the corresponding output of the circuit $(Y_{2} Y_{1} Y_{0})$ will be equal to ____ 3

Discussion

38.	An aircraft executes a horizontal loop on a track at a speed of 720 km/h with its wings banked at 15∘. What is the radius of the loop? (take tan15∘=0.27) and g=10 ms−2
Answer» An aircraft executes a horizontal loop on a track at a speed of $720 k m / h$ with its wings banked at $15^{\circ}$ . What is the radius of the loop? (take $t a n 15^{\circ} = 0.27$ ) and $g = 10 m s^{- 2}$

Discussion

39.	Two wires of resistance R1 and R2 have temperature co-efficient of resistance α1 and α2 respectively. These are joined in series. The effective temperature co-efficient of resistance is
Answer» Two wires of resistance $R_{1}$ and $R_{2}$ have temperature co-efficient of resistance $α_{1}$ and $α_{2}$ respectively. These are joined in series. The effective temperature co-efficient of resistance is

Discussion

40.	The eye can be regarded as a single refracting surface. The radius of curvature of this surface is equal to that of cornea 7.8 mm. This surface separates two media of refractive indices 1 and 1.34. Calculate the distance from the refracting surface at which a parallel beam of light will come to focus.
Answer» The eye can be regarded as a single refracting surface. The radius of curvature of this surface is equal to that of cornea $7.8 mm$ . This surface separates two media of refractive indices $1$ and $1.34$ . Calculate the distance from the refracting surface at which a parallel beam of light will come to focus.

Discussion

41.	An insulator solid sphere of radius R is charged in a uniform manner such that volume charge density p=A/r where A is constant, r is distance from the centre. Electric field strength at any inside point at a radial distance r is?
Answer» An insulator solid sphere of radius R is charged in a uniform manner such that volume charge density p=A/r where A is constant, r is distance from the centre. Electric field strength at any inside point at a radial distance r is?

Discussion

42.	Suppose that a box is accelerating at a rate of 2 m s−2. If the net force is tripled and the mass is doubled, then what is the new acceleration of the box?
Answer» Suppose that a box is accelerating at a rate of $2 m s^{- 2}$ . If the net force is tripled and the mass is doubled, then what is the new acceleration of the box?

Discussion

43.	A galvanometer having resistance of 8 Ω & 50 divisions on both sides has figure of merit 2 mA/division. The resistance that should be connected in series such that it can be used as voltmeter upto 20 V is
Answer» A galvanometer having resistance of $8 Ω$ & 50 divisions on both sides has figure of merit $2 m A / d i v i s i o n$ . The resistance that should be connected in series such that it can be used as voltmeter upto 20 V is

Discussion

44.	A p−n junction shown in the figure can act as a rectifier. An alternating current source (V) is connected in the circuit.The current (I) in the resistor (R) can be shown by
Answer» A $p - n$ junction shown in the figure can act as a rectifier. An alternating current source $(V)$ is connected in the circuit. The current $(I)$ in the resistor $(R)$ can be shown by

Discussion

45.	The resistances in the two arms of the meter bridge are 5Ω and RΩ, respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6, the resistance R is
Answer» The resistances in the two arms of the meter bridge are $5 Ω a n d R Ω$ , respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6, the resistance R is

45.

The resistances in the two arms of the meter bridge are 5Ω and RΩ, respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6, the resistance R is

Answer»

The resistances in the two arms of the meter bridge are $5 Ω a n d R Ω$ , respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6, the resistance R is

Discussion

46.	Two spheres are placed in a horizontal plane with kinetic energies (KE)A=8 J and (KE)B=18 J as shown in figure. If both the spheres collide elastically, find the speed of both the spheres after collision. Both the spheres have the same mass m=1 kg.
Answer» Two spheres are placed in a horizontal plane with kinetic energies $(K E)_{A} = 8 J$ and $(K E)_{B} = 18 J$ as shown in figure. If both the spheres collide elastically, find the speed of both the spheres after collision. Both the spheres have the same mass $m = 1 kg$ .

Discussion

47.	Three voltmeters A, B and C having resistances R, 1.5R and 3R, respectively are used in a circuit as shown when a potential difference is applied between X and Y, the reading of the voltmeters are V1,V2 and V3 respectively then:
Answer» Three voltmeters A, B and C having resistances R, 1.5R and 3R, respectively are used in a circuit as shown when a potential difference is applied between X and Y, the reading of the voltmeters are $V_{1}, V_{2}$ and $V_{3}$ respectively then:

47.

Three voltmeters A, B and C having resistances R, 1.5R and 3R, respectively are used in a circuit as shown when a potential difference is applied between X and Y, the reading of the voltmeters are V1,V2 and V3 respectively then:

Answer»

Three voltmeters A, B and C having resistances R, 1.5R and 3R, respectively are used in a circuit as shown when a potential difference is applied between X and Y, the reading of the voltmeters are $V_{1}, V_{2}$ and $V_{3}$ respectively then:

Discussion

48.	The FBD of mass M in the figure shown is
Answer» The $F B D$ of mass $M$ in the figure shown is

Discussion

49.	The frequency response of a linear, time -invarient system is given by H(f)=51+j10πf. The step response of the system is
Answer» The frequency response of a linear, time -invarient system is given by $H (f) = \frac{5}{1 + j 10 π f} .$ The step response of the system is

Discussion

50.	A positive charge is moving towards a person. The direction of magnetic field lines will be in:
Answer» A positive charge is moving towards a person. The direction of magnetic field lines will be in:

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A boy is rotating in a circular motion, a stone of mass 500 gm by using a string of50 cm length with a speed of 10 cm/s. What will be the work done by the force applied by the boy?

How many significant figures are their in1. 2 kg2. 2

The frequency of oscillation of current in the inductor is

A bi-convex thin lens is prepared from glass (μ=1.5), the two bounding surfaces having equal radii of 25 cm each. One of the surface is silvered from outside. Where should an object be placed before this lens such that the image is formed at the object position itself?

A body moving with uniform retardation cover 3km before its speed is reduced to half of its initial value. It comes to rest in another distance of

A wheel starting from rest is uniformly accelerated at 4 rad/s2 for 10 seconds . It is allowed to rotate uniformly for the next 10 seconds and is finally brought to rest in the next 10 seconds. Find the total angle rotated by the wheel.

If speed of sound in a gas at 127^° C is 400 m/s, then time taken by sound pulse to travel a dis†an ce 2 km between two points in gas column if temperature between the points vary linearly from 127^° C to 627^° C is

The following figure shows the displacement versus time graph for two particles A and B executing simple harmonic motions. The ratio of their maximum velocities (respectively) is

A wire (fixed at both ends) of length l having tension T and radius r vibrates with natural frequency f. Another wire of same metal with length 2l having tension 2T and radius 2r will vibrate with natural frequency

A resistance of 20 ohms is connected to a source of an alternating potential V=220 sin(100 πt). The time taken by the current to change from its peak value to r.m.s value is

A photon of energy 8 eV is incident on a metal surface of threshold frequency 1.6×1015Hz, then the maximum kinetic energy of photoelectrons emitted is (h=6.6×10−34Js)

If the coefficient of friction between an insect and bowl is μ and the radius of the bowl is R. Then the maximum height to which the insect can crawl in the bowl is

Does raincoat increase angle of contact ? If yes then how come it increases surface tension and prevents penetration of water?

In Second class Lever _______is in the middle between the _________and the __________

Three bars of copper ( modulus of elasticity Y)having length L and 2L and 3 l and area of cross section A, 2A and 3A are joined rigidly end-to-end compound rod subjected to a stretching force f find the net modulus of elasticity of the system of wires.

Area of cross section of large tank is 0.5 m² . it has an opening near the bottom having area of cross section 1 cm² a load of 20 kg is applied on the water at the top. find velocity of water coming out of the opening at the time when height of water level is 50 cm above the bottom?

A spring of spring constant 5 x10^3 N/m is stretched initially by 4 cm from the unstretched position. Then work required to stretch it further byanother 6 cm is(1) 5 J(3) 10 J(2) 2.5 J(4) 20 J

57.A tuning fork gives 4 beats with 50 cm length of sonometer wire. If the length of the wire is shortened by 1 cm, the number of beats is still the same. The frequency of the fork is ?

According to Joule's law of heating, the heat produced is given by H=I2 Rt, where I is current, R is resistance and t is the time. If the errors in the measurement of I,R and t are 3 %, 4 % and 6 % respectively, then the error in measurement of H is:

If velocity of a particle moving along a straight line changes sinusoidally with time as shown in given graph. The average speed over time interval t=0 to t=2(2n−1) second, n being any positive interget, is xπ m/s. Value of x is (Answer upto 2 decimal digits)

The terminal velocity of a raindrop of radius 0.3 mm falling through the air of viscosity 1.8×10−5 Ns/m2 is equal to (Consider density of raindrop as 103kg/m3,acceleration due to gravity g=9.8m/s2and Neglect density of air)

Prove that:(i) tan 4π-cos3π2-sin5π6cos2π3=14(ii) sin13π3sin8π3+cos2π3sin5π6=12(iii) sin 13π3sin2π3+cos4π3sin13π6=12(iv) sin10π3cos13π6+cos8π3sin5π6=-1(v) tan5π4cot9π4+tan17π4cot15π4=0

Two particles A and B are moving with uniform velocities as shown in the figure given below at t=0. Find out the shortest distance between the two particles.

An α particle is accelerated through a potential difference of V volts. The de Broglie's wavelength associated with it is:

Consider the circuit given below:The value of input resistance Rin is _____102.38

A cart of mass 50 kg is moving on a straight track with a speed of 12 m/s. A mass of 10 kg is gently put into the cart. What will be the velocity of the cart after this?

State any two laws of simple pendulu

A particle is moving with a velocity →v=k(y^i+x^j), where k is a constant. The general equation for its path is:

There is a current of 20 A in a wire of cross-sectional area 0.01 cm2. If number of free electrons per cubic metre is 1029, then the drift velocity will be

A particle is projected from the ground. If the equation of the trajectory is y = x - x22 , then the time of flight is

A small disc is set rolling with a speed v on the horizontal part of the track of the previous problem from right to left. To what height will it climb up the curved part ?

Constant power P is supplied to a particle having mass m, initially at rest. Choose correct graph between distance covered (s) and time taken (t).

Consider the circuit shown in the figure below:If the three bit input to the circuit is (X2X1X0)=101, then the decimal equivalent of the corresponding output of the circuit (Y2Y1Y0) will be equal to ____3

An aircraft executes a horizontal loop on a track at a speed of 720 km/h with its wings banked at 15∘. What is the radius of the loop? (take tan15∘=0.27) and g=10 ms−2

Two wires of resistance R1 and R2 have temperature co-efficient of resistance α1 and α2 respectively. These are joined in series. The effective temperature co-efficient of resistance is

An insulator solid sphere of radius R is charged in a uniform manner such that volume charge density p=A/r where A is constant, r is distance from the centre. Electric field strength at any inside point at a radial distance r is?

Suppose that a box is accelerating at a rate of 2 m s−2. If the net force is tripled and the mass is doubled, then what is the new acceleration of the box?

A galvanometer having resistance of 8 Ω &amp; 50 divisions on both sides has figure of merit 2 mA/division. The resistance that should be connected in series such that it can be used as voltmeter upto 20 V is

A p−n junction shown in the figure can act as a rectifier. An alternating current source (V) is connected in the circuit.The current (I) in the resistor (R) can be shown by

The resistances in the two arms of the meter bridge are 5Ω and RΩ, respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6, the resistance R is

Two spheres are placed in a horizontal plane with kinetic energies (KE)A=8 J and (KE)B=18 J as shown in figure. If both the spheres collide elastically, find the speed of both the spheres after collision. Both the spheres have the same mass m=1 kg.

Three voltmeters A, B and C having resistances R, 1.5R and 3R, respectively are used in a circuit as shown when a potential difference is applied between X and Y, the reading of the voltmeters are V1,V2 and V3 respectively then:

The FBD of mass M in the figure shown is

The frequency response of a linear, time -invarient system is given by H(f)=51+j10πf. The step response of the system is

A positive charge is moving towards a person. The direction of magnetic field lines will be in:

In Second class Lever ___is in the middle between the _and the ______

A galvanometer having resistance of 8 Ω & 50 divisions on both sides has figure of merit 2 mA/division. The resistance that should be connected in series such that it can be used as voltmeter upto 20 V is