50278 + Interview Questions in Physics Page 288 InterviewSolution

14351.	A domestic refrigerator is working between the melting ice temperature and the atmosphere at 17∘ C. The energy which must be supplied to freeze one kg of water already at 0∘C is(Assume the laent heat for freezing be 80 kcal)
Answer» A domestic refrigerator is working between the melting ice temperature and the atmosphere at $17^{\circ} C$ . The energy which must be supplied to freeze one $kg$ of water already at $0^{\circ} C$ is (Assume the laent heat for freezing be $80 kcal$ )

Discussion

14352.	Work done by 1 V battery when switch S is closed in μJis .
Answer» Work done by 1 V battery when switch S is closed in $μ J$ is .

Discussion

14353.	The ratio between total acceleration of the electron in singly ionized helium atom and doubly ionized lithium atom (Both in ground state) is
Answer» The ratio between total acceleration of the electron in singly ionized helium atom and doubly ionized lithium atom (Both in ground state) is

Discussion

14354.	Starting with a sample of pure 66Cu,78 of it decays into Zn in 15 min. The corresponding half- life is
Answer» Starting with a sample of pure $^{66} C u, \frac{7}{8}$ of it decays into $Z n$ in $15 min$ . The corresponding half- life is

Discussion

14355.	A block of mass m moving with velocity v0 on a smooth horizontal surface hits the spring of constant K as shown. The maximum compression in spring is
Answer» A block of mass $m$ moving with velocity $v_{0}$ on a smooth horizontal surface hits the spring of constant $K$ as shown. The maximum compression in spring is

Discussion

14356.	A cubical block of side a is moving with velocity v on a horizontal smooth plane as shown. It hits a ridge at point O. The angular speed of the block after it hits O is
Answer» A cubical block of side $a$ is moving with velocity $v$ on a horizontal smooth plane as shown. It hits a ridge at point $O$ . The angular speed of the block after it hits $O$ is

Discussion

14357.	27.(1)What happens to the electrostatic force when both charges are doubled? (2) what happens to the electrostatic force when distance between the charges is doubled? (3) what happens to the gravitational force when masses of both the bodies as well as distance between them is doubled?
Answer» 27.(1)What happens to the electrostatic force when both charges are doubled? (2) what happens to the electrostatic force when distance between the charges is doubled? (3) what happens to the gravitational force when masses of both the bodies as well as distance between them is doubled?

Discussion

14358.	Two polaroids P1 and P2 are placed with their axis perpendicular to each other. Unpolarised light I0 is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its axis makes an angle 45o with that of P1. The intensity of transmitted light through P2 is
Answer» Two polaroids $P_{1}$ and $P_{2}$ are placed with their axis perpendicular to each other. Unpolarised light $I_{0}$ is incident on $P_{1}$ . A third polaroid $P_{3}$ is kept in between $P_{1}$ and $P_{2}$ such that its axis makes an angle $45^{o}$ with that of $P_{1}$ . The intensity of transmitted light through $P_{2}$ is

Discussion

14359.	Gas molecules has RMS speed 200 m/s at 27∘C and 1 atm pressure. If the RMS speed changes to x√3 m/s when temperature becomes 127∘C and pressure becomes 2 atm, then the value of x is
Answer» Gas molecules has RMS speed $200 m/s$ at $27^{\circ} C$ and $1 atm$ pressure. If the RMS speed changes to $\frac{x}{\sqrt{3}} m/s$ when temperature becomes $127^{\circ} C$ and pressure becomes $2 atm$ , then the value of $x$ is

Discussion

14360.	Sketch the graphs of the following functions:f(x) = cot2 x
Answer» Sketch the graphs of the following functions: f(x) = cot² x

Discussion

14361.	CH3-CH2-CH2-CHO IT'S NAME IS ?
Answer» CH3-CH2-CH2-CHO IT'S NAME IS ?

Discussion

14362.	A car moving at a constant velocity, comes to rest upon the application of brakes. The motion of the car is shown with the help of the graph. Find the displacement of the car.
Answer» A car moving at a constant velocity, comes to rest upon the application of brakes. The motion of the car is shown with the help of the graph. Find the displacement of the car.

Discussion

14363.	In the circuit shown in figure, E1 and E2 are two ideal sources of unknown emfs. Current flowing through resistor of resistance R Ω is 2 A and through resistor of resistance 4 Ω is 3 A as shown. If potential difference across 6 Ω resistance is VA−VB=10 V, then the value of (E2−E1)R( in V.Ω) is
Answer» In the circuit shown in figure, $E_{1}$ and $E_{2}$ are two ideal sources of unknown emfs. Current flowing through resistor of resistance $R Ω$ is $2 A$ and through resistor of resistance $4 Ω$ is $3 A$ as shown. If potential difference across $6 Ω$ resistance is $V_{A} - V_{B} = 10 V$ , then the value of $(E_{2} - E_{1}) R$ ( in $V . Ω$ ) is

Discussion

14364.	The resistance of the bulb filament is 100 Ω at a temperature of 100∘ C. If its temperature co-efficient of resistance be 0.005 per ∘ C, its resistance will become 200 Ω at a temperature
Answer» The resistance of the bulb filament is 100 $Ω$ at a temperature of 100 $^{\circ}$ C. If its temperature co-efficient of resistance be 0.005 per $^{\circ}$ C, its resistance will become 200 $Ω$ at a temperature

Discussion

14365.	A pendulum bob of mass m carrying a charge q is at rest with its string making an angle θ with the vertical in a uniform horizontal electric field E. The tension in the string is
Answer» A pendulum bob of mass $m$ carrying a charge $q$ is at rest with its string making an angle $θ$ with the vertical in a uniform horizontal electric field $E$ . The tension in the string is

Discussion

14366.	An object of m kg with a speed of v m/s strikes a wall at an angle θ and rebounds at the same speed and same angle. The magnitude of the change in momentum of the object will be
Answer» An object of $m k g$ with a speed of $v m / s$ strikes a wall at an angle $θ$ and rebounds at the same speed and same angle. The magnitude of the change in momentum of the object will be

Discussion

14367.	The electron in a hydrogen atom, first jumps from the third excited state to the second excited state, and subsequently, to the first excited state. The ratio of the respective wavelengths λ1λ2 of the photons emitted in this process is
Answer» The electron in a hydrogen atom, first jumps from the third excited state to the second excited state, and subsequently, to the first excited state. The ratio of the respective wavelengths $\frac{λ_{1}}{λ_{2}}$ of the photons emitted in this process is

Discussion

14368.	A uniform magnetic field ¯B=(3^i+4^j+^k) exists in region of space. A semicircular wire of radius 1 m carrying current 1A having its centre at (2, 2, 0) is placed in x-y plane as shown in figure. The force on semicircular wire will be
Answer» A uniform magnetic field $¯ B = (3^i + 4^j +^k)$ exists in region of space. A semicircular wire of radius 1 m carrying current 1A having its centre at (2, 2, 0) is placed in x-y plane as shown in figure. The force on semicircular wire will be

14368.

A uniform magnetic field ¯B=(3^i+4^j+^k) exists in region of space. A semicircular wire of radius 1 m carrying current 1A having its centre at (2, 2, 0) is placed in x-y plane as shown in figure. The force on semicircular wire will be

Answer»

A uniform magnetic field $¯ B = (3^i + 4^j +^k)$ exists in region of space. A semicircular wire of radius 1 m carrying current 1A having its centre at (2, 2, 0) is placed in x-y plane as shown in figure. The force on semicircular wire will be

Discussion

14369.	Dimensional formula for inductance
Answer» Dimensional formula for inductance

Discussion

14370.	Iron-man needs a better suit to resist Thor’s lightning. What should he change to do this, given that he can’t change the dimensions (size and shape) of the suit.
Answer» Iron-man needs a better suit to resist Thor’s lightning. What should he change to do this, given that he can’t change the dimensions (size and shape) of the suit.

Discussion

14371.	For the potentiometer arrangement shown in the figure, length of wire AB is 100 cm and its resistance is 9Ω. The length AC for which the galvanometer G will show zero deflection is
Answer» For the potentiometer arrangement shown in the figure, length of wire AB is 100 cm and its resistance is $9 Ω$ . The length AC for which the galvanometer G will show zero deflection is

Discussion

14372.	For a finite line charge, find the electric field in a direction parallel to the axis of the line charge at point P.
Answer» For a finite line charge, find the electric field in a direction parallel to the axis of the line charge at point $P$ .

Discussion

14373.	75. Two light rays having the same wavelength lambda in vacuum are in phase initially. Then the first ray travels a path L1 throgh a medium of refractive index n1 while the second ray travels a path of length L2 through a medium of refractive index n2. The two waves are then combined to produce interference. The phase difference between the two waves is?
Answer» 75. Two light rays having the same wavelength lambda in vacuum are in phase initially. Then the first ray travels a path L1 throgh a medium of refractive index n1 while the second ray travels a path of length L2 through a medium of refractive index n2. The two waves are then combined to produce interference. The phase difference between the two waves is?

Discussion

14374.	A car accelerating at the rate of 2 m/s2 from rest is carrying a man at the rear end who has a gun in his hand. The car is always moving along + ve x-axis. At t = 4s, the man fires from the gun and the bullet hits a bird at t = 8s. The bird has a position vector:40^i+80^j+^k at the time of firing the bullet. If velocity of project of bullet is v=vxi+vyj+vzk. Take y axis in the horizontal plane. ___
Answer» A car accelerating at the rate of $2 m / s^{2}$ from rest is carrying a man at the rear end who has a gun in his hand. The car is always moving along + ve x-axis. At t = 4s, the man fires from the gun and the bullet hits a bird at t = 8s. The bird has a position vector: $40^i + 80^j +^k$ at the time of firing the bullet. If velocity of project of bullet is $v = v_{x} i + v_{y} j + v_{z} k$ . Take y axis in the horizontal plane. ___

Discussion

14375.	The frequency of light emitted for the transition n=4 to n=2 of the He+ is equal to the transition in H atom corresponding to which of the following ? (correct answer +1, wrong answer -0.25)
Answer» The frequency of light emitted for the transition $n = 4 t o n = 2$ of the $H e^{+}$ is equal to the transition in $H$ atom corresponding to which of the following ? (correct answer +1, wrong answer -0.25)

Discussion

14376.	Two spheres of equal masses are attached to a string of length 2 m as shown in the figure. The string and the spheres are then whirled in a horizontal circle about O at a constant rate. What is the value of the ratio (Tension in the string between P and QTension in the string between P and O)?
Answer» Two spheres of equal masses are attached to a string of length $2 m$ as shown in the figure. The string and the spheres are then whirled in a horizontal circle about $O$ at a constant rate. What is the value of the ratio $(\frac{Tension in the string between P and Q}{Tension in the string between P and O})$ ?

Discussion

14377.	A car travels 8km along east then 15km along and then 15√2km towards south west.the displacement of the car from the starting point isa)7b)24c)10d)25
Answer» A car travels 8km along east then 15km along and then 15√2km towards south west.the displacement of the car from the starting point is a)7 b)24 c)10 d)25

Discussion

14378.	A particle travelling in a straight path in the same direction covers the first half of the distance with a velocity v1 and the second half of the distance with two different velocities v2 and v3 in equal intervals of time. The average velocity of the particle for the entire journey is
Answer» A particle travelling in a straight path in the same direction covers the first half of the distance with a velocity $v_{1}$ and the second half of the distance with two different velocities $v_{2}$ and $v_{3}$ in equal intervals of time. The average velocity of the particle for the entire journey is

Discussion

14379.	If the ratio of intensity of two coherent sources is 4, then the visibility Imax−IminImax+Imin of the fringes is
Answer» If the ratio of intensity of two coherent sources is $4,$ then the visibility $\frac{I_{m a x} - I_{m i n}}{I_{m a x} + I_{m i n}}$ of the fringes is

Discussion

14380.	The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. Then the number of electron striking the target per second is
Answer» The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. Then the number of electron striking the target per second is

Discussion

14381.	Two masses m1 and m2 which are connected with a light string are placed over a frictionless pulley. This set up is placed over a weighing machine as shown in figure. Three combination of masses m1 and m2 are used, in first case m1=6 kg and m2=2 kg, in second case m1=5 kg and m2=3 kg, in the third case m1=4 kg and m2=4 kg. Masses are released from rest. If W1,W2 and W3 be the reading of weighing machine in three cases, then:
Answer» Two masses $m_{1}$ and $m_{2}$ which are connected with a light string are placed over a frictionless pulley. This set up is placed over a weighing machine as shown in figure. Three combination of masses $m_{1}$ and $m_{2}$ are used, in first case $m_{1} = 6 kg$ and $m_{2} = 2 kg$ , in second case $m_{1} = 5 kg$ and $m_{2} = 3 kg$ , in the third case $m_{1} = 4 kg$ and $m_{2} = 4 kg$ . Masses are released from rest. If $W_{1}, W_{2}$ and $W_{3}$ be the reading of weighing machine in three cases, then:

Discussion

14382.	The charge flowing through a resistance R varies with time as Q=at−bt2, where a and b are positive constants. The total heat produced in R for the time interval t=0 to time when current is zero for the first time is -
Answer» The charge flowing through a resistance $R$ varies with time as $Q = a t - b t^{2}$ , where $a$ and $b$ are positive constants. The total heat produced in $R$ for the time interval $t = 0$ to time when current is zero for the first time is -

Discussion

14383.	43.What are all the forces acting on an air bubble. List 20 forces.
Answer» 43.What are all the forces acting on an air bubble. List 20 forces.

Discussion

14384.	A corkball and a tennis ball have same size and shape. Both are pressed with same force. This compresses the tennis ball but the cork ball is not compressed at all. Which of the following statement is true from the above context?
Answer» A corkball and a tennis ball have same size and shape. Both are pressed with same force. This compresses the tennis ball but the cork ball is not compressed at all. Which of the following statement is true from the above context?

Discussion

14385.	68.The horizontal range of projectile is maximum for which angle of projection
Answer» 68.The horizontal range of projectile is maximum for which angle of projection

Discussion

14386.	A particle is moving with velocity \sqrt S (where S is the dis†an ce travelled by the particle )in a circular path of radius 2m .Find the time when †an gential acceleration and centripetal accerleration are equa ential acceleration and centripetal acceleration are equal.
Answer» A particle is moving with velocity \sqrt S (where S is the dis†an ce travelled by the particle )in a circular path of radius 2m .Find the time when †an gential acceleration and centripetal accerleration are equa ential acceleration and centripetal acceleration are equal.

Discussion

14387.	Evaluate ∫cos(−2x+3)dx
Answer» Evaluate $\int cos (- 2 x + 3) d x$

Discussion

14388.	Figure 20.17 shows a spherical Gaussian surface and a charge distribution. When calculating the flux of electric field through the Gaussian surface, the electric field will be due to
Answer» Figure 20.17 shows a spherical Gaussian surface and a charge distribution. When calculating the flux of electric field through the Gaussian surface, the electric field will be due to

Discussion

14389.	Two charged conducting spheres of radii a and b are connected toeach other by a wire. What is the ratio of electric fields at the surfacesof the two spheres? Use the result obtained to explain why chargedensity on the sharp and pointed ends of a conductor is higherthan on its flatter portions.
Answer» Two charged conducting spheres of radii a and b are connected toeach other by a wire. What is the ratio of electric fields at the surfacesof the two spheres? Use the result obtained to explain why chargedensity on the sharp and pointed ends of a conductor is higherthan on its flatter portions.

Discussion

14390.	The potential difference between the terminals of an electric heater is 25 V when it draws a current of 10 A from the source. What current the heater will draw if the potential difference is increased to 30 V?
Answer» The potential difference between the terminals of an electric heater is $25 V$ when it draws a current of $10 A$ from the source. What current the heater will draw if the potential difference is increased to $30 V ?$

Discussion

14391.	An infinitesimally small bar magnet of dipole moment Pm is pointing and moving with the speed v in the x-direction. A small closed circular conducting loop of radius a and negligible self–inductance lies in the y-z plane with its centre at x = 0, and its axis coinciding with the x-axis. The resistance of the loop is R. Assume that the distance x of the magnet from the centre of the loop is much greater than a. The force opposing the motion is ∝1xy. Value of y is ___
Answer» An infinitesimally small bar magnet of dipole moment $P_{m}$ is pointing and moving with the speed v in the x-direction. A small closed circular conducting loop of radius a and negligible self–inductance lies in the y-z plane with its centre at x = 0, and its axis coinciding with the x-axis. The resistance of the loop is R. Assume that the distance x of the magnet from the centre of the loop is much greater than a. The force opposing the motion is $\propto \frac{1}{x^{y}}$ . Value of y is ___

Discussion

14392.	A body is projected vertically upward the time corresponding to height H while ascending and while descending t1 and t2 respectively then the velocity of projection is
Answer» A body is projected vertically upward the time corresponding to height H while ascending and while descending t1 and t2 respectively then the velocity of projection is

Discussion

14393.	A ball dropped freely takes 0.2 seconds to cross the last 6 m distance before hitting the ground. total time of fall is ? ( g =10m/s2 ) 2.9s 3.1s 2.7s 0.2s
Answer» A ball dropped freely takes 0.2 seconds to cross the last 6 m distance before hitting the ground. total time of fall is ? ( g =10m/s^{2 )} ^2.9s ^3.1s ^2.7s ^0.2s

14393.

A ball dropped freely takes 0.2 seconds to cross the last 6 m distance before hitting the ground. total time of fall is ? ( g =10m/s2 ) 2.9s 3.1s 2.7s 0.2s

Answer»

A ball dropped freely takes 0.2 seconds to cross the last 6 m distance before hitting the ground. total time of fall is ? ( g =10m/s^{2 )}

^2.9s

^3.1s

^2.7s

^0.2s

Discussion

14394.	A passenger train of length 60 m travels at a speed of 80 km/hr. Another freight train of length 120 m travels at a speed of 30 km/h. The ratio of times taken by the passenger train to completely cross the freight train when :(i)they are moving in the same direction, and(ii) in the opposite directions is:
Answer» A passenger train of length $60 m$ travels at a speed of $80 km/hr$ . Another freight train of length $120 m$ travels at a speed of $30 km/h$ . The ratio of times taken by the passenger train to completely cross the freight train when : (i)they are moving in the same direction, and (ii) in the opposite directions is:

Discussion

14395.	A rocket, set for vertical firing, weighs 50 kg and contains 450 kg of fuel. It can have maximum exhaust velocity of 2 km/s. What should be its minimum rate of fuel consumption, to just lift it off the launching pad ?Take g=9.8 m/s2
Answer» A rocket, set for vertical firing, weighs $50 kg$ and contains $450 kg$ of fuel. It can have maximum exhaust velocity of $2 km/s$ . What should be its minimum rate of fuel consumption, to just lift it off the launching pad ? Take $g = 9.8 {m/s}^{2}$

Discussion

14396.	A liquid with speed v through a horizontal pipe of cross sectional area A enters into another pipe of double the area of cross-section. The speed of the liquid in the second pipe will be
Answer» A liquid with speed $v$ through a horizontal pipe of cross sectional area $A$ enters into another pipe of double the area of cross-section. The speed of the liquid in the second pipe will be

Discussion

14397.	Which is these is a possible direction of acceleration for a point on a car that is going on a circular track and is speeding up?
Answer» Which is these is a possible direction of acceleration for a point on a car that is going on a circular track and is speeding up?

14397.

Which is these is a possible direction of acceleration for a point on a car that is going on a circular track and is speeding up?

Answer»

Which is these is a possible direction of acceleration for a point on a car that is going on a circular track and is speeding up?

Discussion

14398.	A RC beam of rectangular cross - section of breadth 250 mm and effective depth 450 mm is subjected to a maximum factored shear force of 150 kN. The grade of concrete is M25 and grade of main steel and stirrups are Fe415 and Fe250 respectively. For the area of main steel provided, the design shear strength τcas per IS 456: 2000 is 0.56N/mm2. If the beam is designed for collapse limit state then the spacing of 2 - legged 10 mm vertical stirrups to be provided is mm
Answer» A RC beam of rectangular cross - section of breadth 250 mm and effective depth 450 mm is subjected to a maximum factored shear force of 150 kN. The grade of concrete is M25 and grade of main steel and stirrups are Fe415 and Fe250 respectively. For the area of main steel provided, the design shear strength $τ_{c}$ as per IS 456: 2000 is $0.56 N / m m^{2}$ . If the beam is designed for collapse limit state then the spacing of 2 - legged 10 mm vertical stirrups to be provided is mm

Discussion

14399.	A spherical body having radius 0.5 m is transfering heat to its surrounding through convection. Find the temperature difference between surrounding and the body surface, if the rate of heat transfer is 1.57×105 W. (Convection coefficient,hc=1570 W/m2-K)
Answer» A spherical body having radius $0.5 m$ is transfering heat to its surrounding through convection. Find the temperature difference between surrounding and the body surface, if the rate of heat transfer is $1.57 \times 10^{5} W$ . (Convection coefficient, $h_{c} = 1570 {W/m}^{2} -K$ )

Discussion

14400.	A vehicle, with a horn of frequency n is moving with a velocity of 30 m/s in a direction perpendicular to the straight line joining the observer and the vehicle. The observer perceives the sound to have a frequency n + n1. Then : (Take velocity of sound in air 330 m/s) :(1)n1 = 10 n(2)n1 = –n(3)n1 = 0(4)n1 = 2n
Answer» A vehicle, with a horn of frequency n is moving with a velocity of 30 m/s in a direction perpendicular to the straight line joining the observer and the vehicle. The observer perceives the sound to have a frequency n + n1. Then : (Take velocity of sound in air 330 m/s) : (1) n1 = 10 n (2) n1 = –n (3) n1 = 0 (4) n1 = 2n

Discussion

Explore topic-wise InterviewSolutions in .

A domestic refrigerator is working between the melting ice temperature and the atmosphere at 17∘ C. The energy which must be supplied to freeze one kg of water already at 0∘C is(Assume the laent heat for freezing be 80 kcal)

Work done by 1 V battery when switch S is closed in μJis .

The ratio between total acceleration of the electron in singly ionized helium atom and doubly ionized lithium atom (Both in ground state) is

Starting with a sample of pure 66Cu,78 of it decays into Zn in 15 min. The corresponding half- life is

A block of mass m moving with velocity v0 on a smooth horizontal surface hits the spring of constant K as shown. The maximum compression in spring is

A cubical block of side a is moving with velocity v on a horizontal smooth plane as shown. It hits a ridge at point O. The angular speed of the block after it hits O is

27.(1)What happens to the electrostatic force when both charges are doubled? (2) what happens to the electrostatic force when distance between the charges is doubled? (3) what happens to the gravitational force when masses of both the bodies as well as distance between them is doubled?

Two polaroids P1 and P2 are placed with their axis perpendicular to each other. Unpolarised light I0 is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its axis makes an angle 45o with that of P1. The intensity of transmitted light through P2 is

Gas molecules has RMS speed 200 m/s at 27∘C and 1 atm pressure. If the RMS speed changes to x√3 m/s when temperature becomes 127∘C and pressure becomes 2 atm, then the value of x is

Sketch the graphs of the following functions:f(x) = cot2 x

CH3-CH2-CH2-CHO IT'S NAME IS ?

A car moving at a constant velocity, comes to rest upon the application of brakes. The motion of the car is shown with the help of the graph. Find the displacement of the car.

The resistance of the bulb filament is 100 Ω at a temperature of 100∘ C. If its temperature co-efficient of resistance be 0.005 per ∘ C, its resistance will become 200 Ω at a temperature

A pendulum bob of mass m carrying a charge q is at rest with its string making an angle θ with the vertical in a uniform horizontal electric field E. The tension in the string is

An object of m kg with a speed of v m/s strikes a wall at an angle θ and rebounds at the same speed and same angle. The magnitude of the change in momentum of the object will be

The electron in a hydrogen atom, first jumps from the third excited state to the second excited state, and subsequently, to the first excited state. The ratio of the respective wavelengths λ1λ2 of the photons emitted in this process is

A uniform magnetic field ¯B=(3^i+4^j+^k) exists in region of space. A semicircular wire of radius 1 m carrying current 1A having its centre at (2, 2, 0) is placed in x-y plane as shown in figure. The force on semicircular wire will be

Dimensional formula for inductance

Iron-man needs a better suit to resist Thor’s lightning. What should he change to do this, given that he can’t change the dimensions (size and shape) of the suit.

For the potentiometer arrangement shown in the figure, length of wire AB is 100 cm and its resistance is 9Ω. The length AC for which the galvanometer G will show zero deflection is

For a finite line charge, find the electric field in a direction parallel to the axis of the line charge at point P.

The frequency of light emitted for the transition n=4 to n=2 of the He+ is equal to the transition in H atom corresponding to which of the following ? (correct answer +1, wrong answer -0.25)

Two spheres of equal masses are attached to a string of length 2 m as shown in the figure. The string and the spheres are then whirled in a horizontal circle about O at a constant rate. What is the value of the ratio (Tension in the string between P and QTension in the string between P and O)?

A car travels 8km along east then 15km along and then 15√2km towards south west.the displacement of the car from the starting point isa)7b)24c)10d)25

A particle travelling in a straight path in the same direction covers the first half of the distance with a velocity v1 and the second half of the distance with two different velocities v2 and v3 in equal intervals of time. The average velocity of the particle for the entire journey is

If the ratio of intensity of two coherent sources is 4, then the visibility Imax−IminImax+Imin of the fringes is

The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. Then the number of electron striking the target per second is

The charge flowing through a resistance R varies with time as Q=at−bt2, where a and b are positive constants. The total heat produced in R for the time interval t=0 to time when current is zero for the first time is -

43.What are all the forces acting on an air bubble. List 20 forces.

A corkball and a tennis ball have same size and shape. Both are pressed with same force. This compresses the tennis ball but the cork ball is not compressed at all. Which of the following statement is true from the above context?

68.The horizontal range of projectile is maximum for which angle of projection

A particle is moving with velocity \sqrt S (where S is the dis†an ce travelled by the particle )in a circular path of radius 2m .Find the time when †an gential acceleration and centripetal accerleration are equa ential acceleration and centripetal acceleration are equal.

Evaluate ∫cos(−2x+3)dx

Figure 20.17 shows a spherical Gaussian surface and a charge distribution. When calculating the flux of electric field through the Gaussian surface, the electric field will be due to

Two charged conducting spheres of radii a and b are connected toeach other by a wire. What is the ratio of electric fields at the surfacesof the two spheres? Use the result obtained to explain why chargedensity on the sharp and pointed ends of a conductor is higherthan on its flatter portions.

The potential difference between the terminals of an electric heater is 25 V when it draws a current of 10 A from the source. What current the heater will draw if the potential difference is increased to 30 V?

A body is projected vertically upward the time corresponding to height H while ascending and while descending t1 and t2 respectively then the velocity of projection is

A ball dropped freely takes 0.2 seconds to cross the last 6 m distance before hitting the ground. total time of fall is ? ( g =10m/s2 ) 2.9s 3.1s 2.7s 0.2s

A rocket, set for vertical firing, weighs 50 kg and contains 450 kg of fuel. It can have maximum exhaust velocity of 2 km/s. What should be its minimum rate of fuel consumption, to just lift it off the launching pad ?Take g=9.8 m/s2

A liquid with speed v through a horizontal pipe of cross sectional area A enters into another pipe of double the area of cross-section. The speed of the liquid in the second pipe will be

Which is these is a possible direction of acceleration for a point on a car that is going on a circular track and is speeding up?

A spherical body having radius 0.5 m is transfering heat to its surrounding through convection. Find the temperature difference between surrounding and the body surface, if the rate of heat transfer is 1.57×105 W. (Convection coefficient,hc=1570 W/m2-K)