50278 + Interview Questions in Physics

1.	A charge is distributed uniformly over a ring of radius 'a'. Obtain an expression for the electric intensity E at a point on the axis of the ring. Hence show that points for large distances from the ring, it behaves like a point charge?
Answer» A charge is distributed uniformly over a ring of radius 'a'. Obtain an expression for the electric intensity E at a point on the axis of the ring. Hence show that points for large distances from the ring, it behaves like a point charge?

Discussion

2.	A body is allowed to fall from a height of 100 m. If the Time taken for the first 50m is t1 and for the remaining 50m is t2 then which of the following is correct? And reason1. t1=t2. 2. t1>t2. 3.t1
Answer» A body is allowed to fall from a height of 100 m. If the Time taken for the first 50m is t1 and for the remaining 50m is t2 then which of the following is correct? And reason 1. t1=t2. 2. t1>t2. 3.t1

Discussion

3.	A solid sphere of radius R has a charge Q distributed in its volume with a charge density ρ=kra, where k and a are constants and r is the distance from its centre. If the electric field at r=R/2 is 1/8 times that at r=R, find the value of a.
Answer» A solid sphere of radius $R$ has a charge $Q$ distributed in its volume with a charge density $ρ = k r^{a}$ , where $k$ and $a$ are constants and $r$ is the distance from its centre. If the electric field at $r = R / 2$ is 1/8 times that at $r = R$ , find the value of $a$ .

Discussion

4.	An adiabatic cylindrical chamber with a frictionless movable piston has been placed on a smooth horizontal surface as shown. One mole of an ideal monotonic gas is enclosed inside the chamber. Mass of the piston is M and mass of the remaining chamber including the gas is 4M. The gas is at atmospheric pressure and temperature. A particle of mass M moving horizontally with speed v, strikes the piston elastically. Find the change in temperature of the gas when the compression is maximum. [R is the ideal gas constant]
Answer» An adiabatic cylindrical chamber with a frictionless movable piston has been placed on a smooth horizontal surface as shown. One mole of an ideal monotonic gas is enclosed inside the chamber. Mass of the piston is $M$ and mass of the remaining chamber including the gas is $4 M$ . The gas is at atmospheric pressure and temperature. A particle of mass $M$ moving horizontally with speed $v$ , strikes the piston elastically. Find the change in temperature of the gas when the compression is maximum. [ $R$ is the ideal gas constant]

Discussion

5.	A particle is projected with velocity of u=30^i+40^j . Its velocity (in m/s) after 2 seconds is (Take g=10 m/s2)
Answer» A particle is projected with velocity of $u = 30^i + 40^j$ . Its velocity (in $m / s$ ) after $2$ seconds is (Take $g = 10 m / s^{2}$ )

Discussion

6.	Two long and parallelstraight wires A and B carrying currents of 8.0 A and 5.0 A in thesame direction are separated by a distance of 4.0 cm. Estimate theforce on a 10 cm section of wire A.
Answer» Two long and parallel straight wires A and B carrying currents of 8.0 A and 5.0 A in the same direction are separated by a distance of 4.0 cm. Estimate the force on a 10 cm section of wire A.

Discussion

7.	Three particles A (m=2kg) B (m=1kg) and C (m=1kg) are placed on the vertices P,Q,R respectively of an equilateral triangle PQR. Velocity of A is 1m/s along PQ, B is 1m/s along QR, and C is 1m/s along RP. What is velocity of the centre of mass?
Answer» Three particles A (m=2kg) B (m=1kg) and C (m=1kg) are placed on the vertices P,Q,R respectively of an equilateral triangle PQR. Velocity of A is 1m/s along PQ, B is 1m/s along QR, and C is 1m/s along RP. What is velocity of the centre of mass?

Discussion

8.	Find the charge and potential drop across the capacitor C4 in the given circuit ?
Answer» Find the charge and potential drop across the capacitor $C_{4}$ in the given circuit ?

Discussion

9.	If an object is held at a distance of 60 cm from a convex mirror of focal length 20 cm. At what distance from the convex mirror, should a plane mirror be held, so that images in the two mirrors coincide
Answer» If an object is held at a distance of 60 cm from a convex mirror of focal length 20 cm. At what distance from the convex mirror, should a plane mirror be held, so that images in the two mirrors coincide

Discussion

10.	35. If distance between earth and sun is increased by 2% then find percentage change in gravitational force acting between them.
Answer» 35. If distance between earth and sun is increased by 2% then find percentage change in gravitational force acting between them.

Discussion

11.	From the top of a tower of height 40 m a ball, isprojected upward with a speed of 20 ms at anelevation of 30^° . The ratio of the total time takenby the ball to hit the ground to its time to comeback at the same level is (g = 10 ms2)
Answer» From the top of a tower of height 40 m a ball, isprojected upward with a speed of 20 ms at anelevation of 30^° . The ratio of the total time takenby the ball to hit the ground to its time to comeback at the same level is (g = 10 ms2)

Discussion

12.

What are the initial position vector →ri and final position vector →rf, both in unit-vector notation? What is the x component of displacement Δ→r? (i) Position vector →ri (x) 5^i−3^j−1^k (ii) Postion vector →rf (y) −2^i−4^j+1^k (iii) x-component of displacement Δ→r (z) 7^i+1^j−2^k

Answer»

What are the initial position vector ${\to r}_{i}$ and final position vector ${\to r}_{f}$ , both in unit-vector notation? What is the x component of displacement $Δ \to r$ ?

(i)	Position vector ${\to r}_{i}$	(x)	$5^i - 3^j - 1^k$
(ii)	Postion vector ${\to r}_{f}$	(y)	$- 2^i - 4^j + 1^k$
(iii)	x-component of displacement $Δ \to r$	(z)	$7^i + 1^j - 2^k$

Discussion

13.	Find electric field due to finite line charge at point P.
Answer» Find electric field due to finite line charge at point $P$ .

Discussion

14.	In the circuit shown in figure neglecting source resistance, the voltmeter and ammeter readings will respectively be
Answer» In the circuit shown in figure neglecting source resistance, the voltmeter and ammeter readings will respectively be

Discussion

15.	100 g of ice (latent heat 80 cal g−1), at 0∘C is mixed with 100 g of water (specific heat 1 cal g−1/∘C ) at 80∘C. The final temperature of the mixture will be
Answer» $100 g$ of ice (latent heat $80 {cal g}^{- 1}$ ), at $0^{\circ} C$ is mixed with $100 g$ of water (specific heat $1 {cal g}^{- 1} /^{\circ} C$ ) at $80^{\circ} C$ . The final temperature of the mixture will be

Discussion

16.	An engine does 41,000 J of useful work. If it sinks 9,000 J of energy in the form of heat to its cold reservoir, find the heat energy supplied to the engine's hot reservoir?
Answer» An engine does 41,000 J of useful work. If it sinks 9,000 J of energy in the form of heat to its cold reservoir, find the heat energy supplied to the engine's hot reservoir?

Discussion

17.	A non conducting sphere of radius R has a spherical cavity of radius R/2 as shown .the solid part of sphere has a uniform vol. Charge density p. Find magnitude and direction of electric field at a pt a) O b) A ( O IS AT CENTRE, A IS AT SURFACE OF SPHERE OF RADIUS R)
Answer» A non conducting sphere of radius R has a spherical cavity of radius R/2 as shown .the solid part of sphere has a uniform vol. Charge density p. Find magnitude and direction of electric field at a pt a) O b) A ( O IS AT CENTRE, A IS AT SURFACE OF SPHERE OF RADIUS R)

Discussion

18.	A positively charged particle having charge q and mass m moving with velocity v0^i enters a region in which magnetic field →B=−B0^k exists. The magnetic field region extends from x=0 to x=d. Then the time spent by the particle in magnetic field if d is equal to 1.5mvqB
Answer» A positively charged particle having charge $q$ and mass $m$ moving with velocity $v_{0}^i$ enters a region in which magnetic field $\to B = - B_{0}^k$ exists. The magnetic field region extends from $x = 0$ to $x = d$ . Then the time spent by the particle in magnetic field if $d$ is equal to $\frac{1.5 m v}{q B}$

Discussion

19.	A brass rod of length 1 m is fixed to a vertical wall at one end, with the other end kept free to expand. When the temperature of the rod increases by 120∘C, the length increases by 3 cm. What is the strain?
Answer» A brass rod of length $1 m$ is fixed to a vertical wall at one end, with the other end kept free to expand. When the temperature of the rod increases by $120^{\circ} C$ , the length increases by $3 cm$ . What is the strain?

Discussion

20.	Three weights W, 2W and 2W are connected to identical springs suspended form rigid lkhorizontal rod. The assembly of the rod and the weights fall freely. The positions of the weights from the rod are such that
Answer» Three weights W, 2W and 2W are connected to identical springs suspended form rigid lkhorizontal rod. The assembly of the rod and the weights fall freely. The positions of the weights from the rod are such that

Discussion

21.	As shown in the figure, a triangular sheet is removed from a uniform rectangular sheet. Then, shift of the centre of mass for the new shape will be:
Answer» As shown in the figure, a triangular sheet is removed from a uniform rectangular sheet. Then, shift of the centre of mass for the new shape will be:

Discussion

22.	Calculate the length of a second's pendulum (the pendulum which ticks seconds).
Answer» Calculate the length of a second's pendulum (the pendulum which ticks seconds).

Discussion

23.	A ball dropped from a balloon at rest clears a tower 81m high during the last quater second of its journey . Find the height of the balloon and velocity of the body when it reaches the ground.options are(a) 2684.2m , 324.38 m/s(b)2687.3m , 321.12 m/s(c)2786.90m,271.87 m/s(d)2897.7m , 321.12m/s
Answer» A ball dropped from a balloon at rest clears a tower 81m high during the last quater second of its journey . Find the height of the balloon and velocity of the body when it reaches the ground.options are(a) 2684.2m , 324.38 m/s(b)2687.3m , 321.12 m/s(c)2786.90m,271.87 m/s(d)2897.7m , 321.12m/s

Discussion

24.	An elevator is going up. The variation in the velocity of the elevator is as shown in the graph. What is the height to which the elevator takes the passengers?
Answer» An elevator is going up. The variation in the velocity of the elevator is as shown in the graph. What is the height to which the elevator takes the passengers?

Discussion

25.	Two blocks ′A′ and ′B′ each of mass ′m′ are placed on a smooth horizontal surface. Two horizontal forces F and 2F are applied on both the blocks ′A′ and ′B′ respectively as shown in figure. The block A does not slide on block B. Then the normal reaction acting between the two blocks is:Report n, if the answer in nF
Answer» Two blocks $^{'} A^{'}$ and $^{'} B^{'}$ each of mass $^{'} m^{'}$ are placed on a smooth horizontal surface. Two horizontal forces $F$ and $2 F$ are applied on both the blocks $^{'} A^{'}$ and $^{'} B^{'}$ respectively as shown in figure. The block $A$ does not slide on block $B$ . Then the normal reaction acting between the two blocks is: Report $n$ , if the answer in $n F$

Discussion

26.	An isotropic point source having radiation power P is located on the axis of an ideal mirror plate. The distance between the source and the plate centre is n times the radius of the plate. In terms of photon theory find the force that light exerts on the plate.(c denotes speed of light) ?
Answer» An isotropic point source having radiation power P is located on the axis of an ideal mirror plate. The distance between the source and the plate centre is n times the radius of the plate. In terms of photon theory find the force that light exerts on the plate.(c denotes speed of light) ?

Discussion

27.	The potential Energy of a particle in a force field is U = A/r^2 - B/r where A and B are positive constants and r is the distance of particle from the center of the field. For stable equilibrium, the distance of the particle is?
Answer» The potential Energy of a particle in a force field is U = A/r^2 - B/r where A and B are positive constants and r is the distance of particle from the center of the field. For stable equilibrium, the distance of the particle is?

Discussion

28.	If →a,→b,→c form a left handed orthogonal system and →a⋅→a=4,→b⋅→b=9,→c⋅→c=16 then [→a →b →c] is equal to
Answer» If $\to a, \to b, \to c$ form a left handed orthogonal system and $\to a \cdot \to a = 4, \to b \cdot \to b = 9, \to c \cdot \to c = 16$ then $[\to a \to b \to c]$ is equal to

Discussion

29.	A point charge +Q is placed just outside an imaginary hemispherical surface of radius R as shown in the figure. The electric flux passing through the curved surface of the hemisphere is(Angle subtended by the diameter at position of charge is 2θ)
Answer» A point charge $+ Q$ is placed just outside an imaginary hemispherical surface of radius $R$ as shown in the figure. The electric flux passing through the curved surface of the hemisphere is (Angle subtended by the diameter at position of charge is $2 θ$ )

Discussion

30.	In a hypothetical situation if a point charge q is brought from infinity (slowly so that heat developed in the shell is negligible) and placed at the centre of a conducting neutral spherical shell of inner radius a and outer radius b, then work done by external agent is calculated to be ka2na−kq22b .Find the value of n (Give integer value)
Answer» In a hypothetical situation if a point charge $q$ is brought from infinity (slowly so that heat developed in the shell is negligible) and placed at the centre of a conducting neutral spherical shell of inner radius $a$ and outer radius $b$ , then work done by external agent is calculated to be $\frac{k a^{2}}{n a} - \frac{k q^{2}}{2 b}$ .Find the value of $n$ (Give integer value)

Discussion

31.	The horn of a car emits sound with a dominant frequency of 2400 Hz. What will be the apparent dominant frequency heard by a person standing on the road in front of the car if the car is approaching at 18.0 km/h? Speed of sound in air = 340 m/s.
Answer» The horn of a car emits sound with a dominant frequency of 2400 Hz. What will be the apparent dominant frequency heard by a person standing on the road in front of the car if the car is approaching at 18.0 km/h? Speed of sound in air = 340 m/s.

Discussion

32.	The resistance of a resistor is 100 ohm at a temperature 100^° C. Resistance become double at a temperature T_o. If temperature coefficient ofresistance is 0.005/^° C, T_o is 1)1300^° C(2) 200^° C (3) 600^° C(4400^° C
Answer» The resistance of a resistor is 100 ohm at a temperature 100^° C. Resistance become double at a temperature T_o. If temperature coefficient ofresistance is 0.005/^° C, T_o is 1)1300^° C(2) 200^° C (3) 600^° C(4400^° C

Discussion

33.	a thin rod of mass M and length L is bent at mid point A to make an angle of 60degree.the moment of inertia of the rod about an axis passing through the point A and perpendicular to the plane of rod would be
Answer» a thin rod of mass M and length L is bent at mid point A to make an angle of 60degree.the moment of inertia of the rod about an axis passing through the point A and perpendicular to the plane of rod would be

Discussion

34.	A particle of charge q and velocity v passes undeflected though a space with non-zero electric field E and magnetic field B. The undeflecting conditions will hold if
Answer» A particle of charge q and velocity v passes undeflected though a space with non-zero electric field E and magnetic field B. The undeflecting conditions will hold if

Discussion

35.	Blocks A and B of masses 2 kg and 3 kg respectively are placed on a smooth ground. If an external force P of magnitude 10 N acts on A as shown, find the force exerted by B on A is
Answer» Blocks $A$ and $B$ of masses $2 k g$ and $3 k g$ respectively are placed on a smooth ground. If an external force $P$ of magnitude $10 N$ acts on $A$ as shown, find the force exerted by $B$ on $A$ is

Discussion

36.

The following apparatus is available in the school laboratory: Battery : 4.5 V Rheostat : Varies battery voltage from 0 to 4.5 V Resistors : 1 Ω and 2 Ω Ammeters : A1 of range 0 to 1 A; Least count 0.05 A : A2 of range 0 to 3 A; Least count 0.1 A Voltmeters : V1 of range 0 to 5 V; Least count 0.1 V : V2 of range 0 to 10 V; Least count 0.5 V The best combination of ammeter and voltmeter for finding the resultant resistance of the two given resistors connected in series would be:(1) ammeter A1 and voltmeter V1(2) ammeter A1 and voltmeter V1(3) ammeter A2 and voltmeter V1 (4) ammeter A2 and voltmeter V2

Answer» The following apparatus is available in the school laboratory:

Battery	:	4.5 V
Rheostat	:	Varies battery voltage from 0 to 4.5 V
Resistors	:	1 Ω and 2 Ω
Ammeters	:	A₁ of range 0 to 1 A; Least count 0.05 A
	:	A₂ of range 0 to 3 A; Least count 0.1 A
Voltmeters	:	V₁ of range 0 to 5 V; Least count 0.1 V
	:	V₂ of range 0 to 10 V; Least count 0.5 V

The best combination of ammeter and voltmeter for finding the resultant resistance of the two given resistors connected in series would be:

(1) ammeter A₁ and voltmeter V₁

(2) ammeter A₁ and voltmeter V₁

(3) ammeter A₂ and voltmeter V₁

(4) ammeter A₂ and voltmeter V₂

Discussion

37.	The surface tension of soap solution is T=0.03 Nm−1. If the size of a soap bubble is increased from a radius of 3 cm to 5 cm, the work done in increasing the size of the soap bubble is
Answer» The surface tension of soap solution is $T = 0.03 {Nm}^{- 1}$ . If the size of a soap bubble is increased from a radius of $3 cm$ to $5 cm$ , the work done in increasing the size of the soap bubble is

Discussion

38.	The objective of an astronomical telescope has a focal length of 100 cm. The telescope is focused for normal vision of distant objects when tube length is 1.1 m. Find magnifying power of the telescope.
Answer» The objective of an astronomical telescope has a focal length of $100 cm$ . The telescope is focused for normal vision of distant objects when tube length is $1.1 m$ . Find magnifying power of the telescope.

Discussion

39.	A coil of mean area 400 cm2 and having 1000 turns, is held perpendicular to a uniform magnetic field of 0.2 T. The coil is turned through 90∘ in 110 seconds. Calculate the change in magnetic flux ?
Answer» A coil of mean area $400 {cm}^{2}$ and having $1000 turns$ , is held perpendicular to a uniform magnetic field of $0.2 T$ . The coil is turned through $90^{\circ}$ in $\frac{1}{10} seconds$ . Calculate the change in magnetic flux ?

Discussion

40.	A block of mass 5 kg is hanging from the top of a cliff. Calculate the speed of wave along this string, if length of the string is 1 m and mass of the string is 5 gms.[Take g=10 m/s2]
Answer» A block of mass $5 kg$ is hanging from the top of a cliff. Calculate the speed of wave along this string, if length of the string is $1 m$ and mass of the string is $5 gms$ . [Take $g = 10 {m/s}^{2}$ ]

Discussion

41.	A current carrying wire is arrangedat any angle in an uniform magnetic field, then:- (1)only force acts on wire (2)only torque acts on wire (3)both (4)none
Answer» A current carrying wire is arrangedat any angle in an uniform magnetic field, then:- (1)only force acts on wire (2)only torque acts on wire (3)both (4)none

Discussion

42.	One end of a U-tube containing mercury is connected to a suction pump and the other end to atmosphere. A small pressure difference is maintained between the two columns. Show that, when the suction pump is removed, the column of mercury in the U-tube executes simple harmonic motion.
Answer» One end of a U-tube containing mercury is connected to a suction pump and the other end to atmosphere. A small pressure difference is maintained between the two columns. Show that, when the suction pump is removed, the column of mercury in the U-tube executes simple harmonic motion.

Discussion

43.	The radius of curvature of curved surface of a plano-convex lens is 15 cm. The refractive index of the lens material is 1.5. The focal length of plano-convex lens is (surroundings is air)
Answer» The radius of curvature of curved surface of a plano-convex lens is $15 cm$ . The refractive index of the lens material is $1.5$ . The focal length of plano-convex lens is (surroundings is air)

Discussion

44.	A particle moves so that its position vector is giveny, whereis a constant.by r coswt x + sin wtWhich of the following is true?
Answer» A particle moves so that its position vector is giveny, whereis a constant.by r coswt x + sin wtWhich of the following is true?

Discussion

45.	plane microwaves are incident on a long slit having a width of 5 cm. if the first diffraction minima is formed at theta= 30.then wavelengt of microwave
Answer» plane microwaves are incident on a long slit having a width of 5 cm. if the first diffraction minima is formed at theta= 30.then wavelengt of microwave

Discussion

46.	A capacitor of capacitance 1 μF is filled with two dielectrics of dielectric constants 4 and 6. What is the new capacitance?
Answer» A capacitor of capacitance $1 μ F$ is filled with two dielectrics of dielectric constants 4 and 6. What is the new capacitance?

46.

A capacitor of capacitance 1 μF is filled with two dielectrics of dielectric constants 4 and 6. What is the new capacitance?

Answer»

A capacitor of capacitance $1 μ F$ is filled with two dielectrics of dielectric constants 4 and 6. What is the new capacitance?

Discussion

47.	39 A particle is projected from the ground with somespeed at an angle 30^° from ground. It is at sameheight at t = 2 s and t = 6 s. The projected speedis(1) 40 m/s(2) 20 m/s(3) 10 m/s(4) 80 m/s
Answer» 39 A particle is projected from the ground with somespeed at an angle 30^° from ground. It is at sameheight at t = 2 s and t = 6 s. The projected speedis(1) 40 m/s(2) 20 m/s(3) 10 m/s(4) 80 m/s

Discussion

48.	Three plane mirrors are arranged mutually perpendicular to each other as shown in the figure. If a point object is placed symmetrically between the mirrors, then the number of distinct images formed will be
Answer» Three plane mirrors are arranged mutually perpendicular to each other as shown in the figure. If a point object is placed symmetrically between the mirrors, then the number of distinct images formed will be

Discussion

49.

If the error in the measurement of momentum of a particle is 50% ,then the error in the measurement of kinetic energy is how much? a)75% b)125%

Answer»

If the error in the measurement of momentum of a particle is 50% ,then the error in the measurement of kinetic energy is how much?

a)75% b)125%

Discussion

50.	the electric potential in the space is given by V=x^2 then electric field at a point (1,1,1)is
Answer» the electric potential in the space is given by V=x^2 then electric field at a point (1,1,1)is

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A charge is distributed uniformly over a ring of radius 'a'. Obtain an expression for the electric intensity E at a point on the axis of the ring. Hence show that points for large distances from the ring, it behaves like a point charge?

A body is allowed to fall from a height of 100 m. If the Time taken for the first 50m is t1 and for the remaining 50m is t2 then which of the following is correct? And reason1. t1=t2. 2. t1>t2. 3.t1

A solid sphere of radius R has a charge Q distributed in its volume with a charge density ρ=kra, where k and a are constants and r is the distance from its centre. If the electric field at r=R/2 is 1/8 times that at r=R, find the value of a.

A particle is projected with velocity of u=30^i+40^j . Its velocity (in m/s) after 2 seconds is (Take g=10 m/s2)

Two long and parallelstraight wires A and B carrying currents of 8.0 A and 5.0 A in thesame direction are separated by a distance of 4.0 cm. Estimate theforce on a 10 cm section of wire A.

Three particles A (m=2kg) B (m=1kg) and C (m=1kg) are placed on the vertices P,Q,R respectively of an equilateral triangle PQR. Velocity of A is 1m/s along PQ, B is 1m/s along QR, and C is 1m/s along RP. What is velocity of the centre of mass?

Find the charge and potential drop across the capacitor C4 in the given circuit ?

If an object is held at a distance of 60 cm from a convex mirror of focal length 20 cm. At what distance from the convex mirror, should a plane mirror be held, so that images in the two mirrors coincide

35. If distance between earth and sun is increased by 2% then find percentage change in gravitational force acting between them.

From the top of a tower of height 40 m a ball, isprojected upward with a speed of 20 ms at anelevation of 30^° . The ratio of the total time takenby the ball to hit the ground to its time to comeback at the same level is (g = 10 ms2)

Find electric field due to finite line charge at point P.

In the circuit shown in figure neglecting source resistance, the voltmeter and ammeter readings will respectively be

100 g of ice (latent heat 80 cal g−1), at 0∘C is mixed with 100 g of water (specific heat 1 cal g−1/∘C ) at 80∘C. The final temperature of the mixture will be

An engine does 41,000 J of useful work. If it sinks 9,000 J of energy in the form of heat to its cold reservoir, find the heat energy supplied to the engine's hot reservoir?

A non conducting sphere of radius R has a spherical cavity of radius R/2 as shown .the solid part of sphere has a uniform vol. Charge density p. Find magnitude and direction of electric field at a pt a) O b) A ( O IS AT CENTRE, A IS AT SURFACE OF SPHERE OF RADIUS R)

A positively charged particle having charge q and mass m moving with velocity v0^i enters a region in which magnetic field →B=−B0^k exists. The magnetic field region extends from x=0 to x=d. Then the time spent by the particle in magnetic field if d is equal to 1.5mvqB

A brass rod of length 1 m is fixed to a vertical wall at one end, with the other end kept free to expand. When the temperature of the rod increases by 120∘C, the length increases by 3 cm. What is the strain?

Three weights W, 2W and 2W are connected to identical springs suspended form rigid lkhorizontal rod. The assembly of the rod and the weights fall freely. The positions of the weights from the rod are such that

As shown in the figure, a triangular sheet is removed from a uniform rectangular sheet. Then, shift of the centre of mass for the new shape will be:

Calculate the length of a second's pendulum (the pendulum which ticks seconds).

A ball dropped from a balloon at rest clears a tower 81m high during the last quater second of its journey . Find the height of the balloon and velocity of the body when it reaches the ground.options are(a) 2684.2m , 324.38 m/s(b)2687.3m , 321.12 m/s(c)2786.90m,271.87 m/s(d)2897.7m , 321.12m/s

An elevator is going up. The variation in the velocity of the elevator is as shown in the graph. What is the height to which the elevator takes the passengers?

An isotropic point source having radiation power P is located on the axis of an ideal mirror plate. The distance between the source and the plate centre is n times the radius of the plate. In terms of photon theory find the force that light exerts on the plate.(c denotes speed of light) ?

The potential Energy of a particle in a force field is U = A/r^2 - B/r where A and B are positive constants and r is the distance of particle from the center of the field. For stable equilibrium, the distance of the particle is?

If →a,→b,→c form a left handed orthogonal system and →a⋅→a=4,→b⋅→b=9,→c⋅→c=16 then [→a →b →c] is equal to

A point charge +Q is placed just outside an imaginary hemispherical surface of radius R as shown in the figure. The electric flux passing through the curved surface of the hemisphere is(Angle subtended by the diameter at position of charge is 2θ)

The horn of a car emits sound with a dominant frequency of 2400 Hz. What will be the apparent dominant frequency heard by a person standing on the road in front of the car if the car is approaching at 18.0 km/h? Speed of sound in air = 340 m/s.

The resistance of a resistor is 100 ohm at a temperature 100^° C. Resistance become double at a temperature T_o. If temperature coefficient ofresistance is 0.005/^° C, T_o is 1)1300^° C(2) 200^° C (3) 600^° C(4400^° C

a thin rod of mass M and length L is bent at mid point A to make an angle of 60degree.the moment of inertia of the rod about an axis passing through the point A and perpendicular to the plane of rod would be

A particle of charge q and velocity v passes undeflected though a space with non-zero electric field E and magnetic field B. The undeflecting conditions will hold if

Blocks A and B of masses 2 kg and 3 kg respectively are placed on a smooth ground. If an external force P of magnitude 10 N acts on A as shown, find the force exerted by B on A is

The surface tension of soap solution is T=0.03 Nm−1. If the size of a soap bubble is increased from a radius of 3 cm to 5 cm, the work done in increasing the size of the soap bubble is

The objective of an astronomical telescope has a focal length of 100 cm. The telescope is focused for normal vision of distant objects when tube length is 1.1 m. Find magnifying power of the telescope.

A coil of mean area 400 cm2 and having 1000 turns, is held perpendicular to a uniform magnetic field of 0.2 T. The coil is turned through 90∘ in 110 seconds. Calculate the change in magnetic flux ?

A block of mass 5 kg is hanging from the top of a cliff. Calculate the speed of wave along this string, if length of the string is 1 m and mass of the string is 5 gms.[Take g=10 m/s2]

A current carrying wire is arrangedat any angle in an uniform magnetic field, then:- (1)only force acts on wire (2)only torque acts on wire (3)both (4)none

One end of a U-tube containing mercury is connected to a suction pump and the other end to atmosphere. A small pressure difference is maintained between the two columns. Show that, when the suction pump is removed, the column of mercury in the U-tube executes simple harmonic motion.

The radius of curvature of curved surface of a plano-convex lens is 15 cm. The refractive index of the lens material is 1.5. The focal length of plano-convex lens is (surroundings is air)

A particle moves so that its position vector is giveny, whereis a constant.by r coswt x + sin wtWhich of the following is true?

plane microwaves are incident on a long slit having a width of 5 cm. if the first diffraction minima is formed at theta= 30.then wavelengt of microwave

A capacitor of capacitance 1 μF is filled with two dielectrics of dielectric constants 4 and 6. What is the new capacitance?

39 A particle is projected from the ground with somespeed at an angle 30^° from ground. It is at sameheight at t = 2 s and t = 6 s. The projected speedis(1) 40 m/s(2) 20 m/s(3) 10 m/s(4) 80 m/s

Three plane mirrors are arranged mutually perpendicular to each other as shown in the figure. If a point object is placed symmetrically between the mirrors, then the number of distinct images formed will be

If the error in the measurement of momentum of a particle is 50% ,then the error in the measurement of kinetic energy is how much? a)75% b)125%

the electric potential in the space is given by V=x^2 then electric field at a point (1,1,1)is