2673 + Interview Questions in Physics Page 43 InterviewSolution

2101.	A force F=(^i+4^j) N acts on the block shown. The force of friction acting on the block is :
Answer» A force $F = (^i + 4^j) N$ acts on the block shown. The force of friction acting on the block is :

Discussion

2102.	In the arrangement shown in figure, pulleys are small and light and the springs are ideal. K1=25π2Nm,K2=2K1,K3=3K1 and K4=4K1 are the force constants of the springs. Calculate the period of small vertical oscillations (in s) of the block of mass m=3 kg
Answer» In the arrangement shown in figure, pulleys are small and light and the springs are ideal. $K_{1} = 25 π^{2} \frac{N}{m}, K_{2} = 2 K_{1}, K_{3} = 3 K_{1}$ and $K_{4} = 4 K_{1}$ are the force constants of the springs. Calculate the period of small vertical oscillations (in $s$ ) of the block of mass $m = 3 kg$

Discussion

2103.	A glass bottle of volume 5 litres is filled with gasoline at room temperature. Accidently, the bottle was left close to an engine exhaust and the temperature rises by 40∘C. Calculate the volume of gasoline that spills out of the glass bottle as a result of this temperature rise.[Take room temperature to be 25∘C, coefficient of linear expansion of glass as 8.5×10−6/∘C, volumetric coefficient of gasoline at 25∘C as 950×10−6/∘C].
Answer» A glass bottle of volume $5 litres$ is filled with gasoline at room temperature. Accidently, the bottle was left close to an engine exhaust and the temperature rises by $40^{\circ} C$ . Calculate the volume of gasoline that spills out of the glass bottle as a result of this temperature rise. [Take room temperature to be $25^{\circ} C$ , coefficient of linear expansion of glass as $8.5 \times 10^{- 6} /^{\circ} C$ , volumetric coefficient of gasoline at $25^{\circ} C$ as $950 \times 10^{- 6} /^{\circ} C$ ].

Discussion

2104.	The power radiated by a black body is P and it radiates maximum energy around the wavelength λ0. If the temperature of the black body is now changed so that it radiates maximum energy around wavelength 3λ04, the power radiated by it will increase by a factor of
Answer» The power radiated by a black body is P and it radiates maximum energy around the wavelength $λ_{0}$ . If the temperature of the black body is now changed so that it radiates maximum energy around wavelength $\frac{3 λ_{0}}{4}$ , the power radiated by it will increase by a factor of

Discussion

2105.	The electric potential varies in space according to the relation V=3x+4y. A particle of mass 0.1kg starts from rest from point (2,3.2) under the influence of this field. The charge on the particle is +1μC. Assume V and (x,y) are in S.I. unitsThe time taken to cross the x - axis is
Answer» The electric potential varies in space according to the relation $V = 3 x + 4 y .$ A particle of mass $0.1 k g$ starts from rest from point $(2, 3.2)$ under the influence of this field. The charge on the particle is $+ 1 μ C .$ Assume $V$ and $(x, y)$ are in S.I. units The time taken to cross the $x$ - axis is

Discussion

2106.	A car sometimes overturns while taking a turn. When it overturns, it is
Answer» A car sometimes overturns while taking a turn. When it overturns, it is

Discussion

2107.	A boat takes t1 time while going downstream between two fixed points A and B, and takes t2 time while going upstream through the same distance. If river does not flow, then the time taken by the boat to cover the same distance is
Answer» A boat takes $t_{1}$ time while going downstream between two fixed points $A$ and $B$ , and takes $t_{2}$ time while going upstream through the same distance. If river does not flow, then the time taken by the boat to cover the same distance is

Discussion

2108.	Two metal cubes A and B of same size are arranged as shown in figure. The extreme ends of the combination are maintained at the indicated temperatures. The arrangement is thermally insulated. The coefficients of thermal conductivity of A and B are 300 W/m ∘C,and 200 W/m ∘C, respectively. After steady state is reached the temperature T of the interface will be ….
Answer» Two metal cubes A and B of same size are arranged as shown in figure. The extreme ends of the combination are maintained at the indicated temperatures. The arrangement is thermally insulated. The coefficients of thermal conductivity of A and B are 300 W/m $^{\circ} C$ ,and 200 W/m $^{\circ} C$ , respectively. After steady state is reached the temperature T of the interface will be ….

Discussion

2109.	Considering the points lying on a straight line joining two fixed charges with equal magnitude and opposite nature, between the charges there is
Answer» Considering the points lying on a straight line joining two fixed charges with equal magnitude and opposite nature, between the charges there is

Discussion

2110.	A glass contains some water at room temperature 20∘C. Refrigerated water is added to it slowly. When the temperature of the glass reaches 10∘C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5 mm of mercury is 20∘C and at 8.9 mm of mercury it is 10∘C.
Answer» A glass contains some water at room temperature $20^{\circ} C$ . Refrigerated water is added to it slowly. When the temperature of the glass reaches $10^{\circ} C$ , small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5 mm of mercury is $20^{\circ} C$ and at 8.9 mm of mercury it is $10^{\circ} C$ .

Discussion

2111.	If an incident ray is directed towards a corner reflector as shown, at what angle(θ) does the reflected ray emerge?
Answer» If an incident ray is directed towards a corner reflector as shown, at what angle $(θ)$ does the reflected ray emerge?

Discussion

2112.	A body of mass 'm' moving with velocity 'v' collides head on elastically with another body of mass '2m' which was initially at rest. The ratio of K.E. of colliding body of mass 'm' before and after collision would be
Answer» A body of mass 'm' moving with velocity 'v' collides head on elastically with another body of mass '2m' which was initially at rest. The ratio of K.E. of colliding body of mass 'm' before and after collision would be

Discussion

2113.	The engine of a train sounds a whistle at frequency (f). The frequency heard by a passenger is
Answer» The engine of a train sounds a whistle at frequency $(f)$ . The frequency heard by a passenger is

Discussion

2114.	In the figure shown below, ma=3 kg and mb=1 kg. String is inextensible and light. Find the acceleration of centre of mass of the system.
Answer» In the figure shown below, $m_{a} = 3 kg$ and $m_{b} = 1 kg$ . String is inextensible and light. Find the acceleration of centre of mass of the system.

Discussion

2115.	From the following displacement-time graph find out the velocity of a moving body
Answer» From the following displacement-time graph find out the velocity of a moving body

Discussion

2116.	A long horizontally fixed wire carries a current of 100A. Directly above and parallel to it is another wire carrying a current of 20 A and weighing 0.04 N m-1 . What should be the separation between the two wires so that the upper wire is just supported by magnetic repulsion?
Answer» A long horizontally fixed wire carries a current of 100A. Directly above and parallel to it is another wire carrying a current of 20 A and weighing 0.04 N m^-1 . What should be the separation between the two wires so that the upper wire is just supported by magnetic repulsion?

Discussion

2117.	A square frame is made using four thin uniform rods of length l each having linear mass densities λ, 2λ, 3λ and 4λ as shown in the figure. Which of the following is correct?
Answer» A square frame is made using four thin uniform rods of length $l$ each having linear mass densities $λ, 2 λ, 3 λ$ and $4 λ$ as shown in the figure. Which of the following is correct?

Discussion

2118.	A small block is shot into each of the four tracks as shown in the options. Each of the tracks rises to the same height. The speed with which the block enters the track is the same in all cases. At the highest point of the track, the normal reaction is maximum in -
Answer» A small block is shot into each of the four tracks as shown in the options. Each of the tracks rises to the same height. The speed with which the block enters the track is the same in all cases. At the highest point of the track, the normal reaction is maximum in -

Discussion

2119.	A student wants to find the absolute pressure of water at a point below the surface of water. He has a barometer and a manometer pressure gauge. The barometer reads 1.3152 bar whereas the manometer pressure gauge reads 0.3152 bar. What is the absolute pressure? (Assume that pressure at one end of the manometer is atmospheric.)
Answer» A student wants to find the absolute pressure of water at a point below the surface of water. He has a barometer and a manometer pressure gauge. The barometer reads $1.3152 bar$ whereas the manometer pressure gauge reads $0.3152 bar$ . What is the absolute pressure? (Assume that pressure at one end of the manometer is atmospheric.)

Discussion

2120.	A flexible wire bent in the form of a circle is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in the figure.The graph of magnitude of induced emf in the coil is represented by
Answer» A flexible wire bent in the form of a circle is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in the figure. The graph of magnitude of induced emf in the coil is represented by

Discussion

2121.	A loop ABCDEFA of straight edges has six corner points A(0,0,0), B(5,0,0), C(5,5,0), D(0,5,0), E(0,5,5), F(0,0,5). The magnetic field in this region is →B = (3^i+4^k) T. The quantity of flux through the loop ABCDEFA (in Wb) is
Answer» A loop $A B C D E F A$ of straight edges has six corner points A(0,0,0), B(5,0,0), C(5,5,0), D(0,5,0), E(0,5,5), F(0,0,5). The magnetic field in this region is $\to B$ = $(3^i + 4^k) T$ . The quantity of flux through the loop $A B C D E F A$ (in $W b$ ) is

Discussion

2122.	One end of a long metallic wire of length L is tied to the ceiling. The other end is tied to a massless spring of spring constant K. A mass m hangs freely from the free end of the spring. The area of cross – section and Young’s modulus of the wire are A and Y respectively. If the mass is slightly pulled down and released, it will oscillate with a time period given by
Answer» One end of a long metallic wire of length L is tied to the ceiling. The other end is tied to a massless spring of spring constant K. A mass m hangs freely from the free end of the spring. The area of cross – section and Young’s modulus of the wire are A and Y respectively. If the mass is slightly pulled down and released, it will oscillate with a time period given by

Discussion

2123.	A planet has mass 110 of that of earth, while radius is 13 that of earth. If a person can throw a stone on earth surface to a height of 90m, then he will be able to throw the stone on that planet to a height
Answer» A planet has mass $\frac{1}{10}$ of that of earth, while radius is $\frac{1}{3}$ that of earth. If a person can throw a stone on earth surface to a height of 90m, then he will be able to throw the stone on that planet to a height

Discussion

2124.	A conductor ABOCD moves along its bisector with a velocity 1 m/s through a perpendicular magnetic field of 1 Wb/m2, as shown in figure. If all the four sides are of 1 m length each, then the induced emf between A and D (in volts) is approximately (upto two decimals)
Answer» A conductor $A B O C D$ moves along its bisector with a velocity $1 m/s$ through a perpendicular magnetic field of $1 {Wb/m}^{2}$ , as shown in figure. If all the four sides are of $1 m$ length each, then the induced emf between A and D (in $volts$ ) is approximately (upto two decimals)

Discussion

2125.	A current I is passing through a wire having two sections P and Q of uniform diameters d and d2 respectively. If the mean drift velocity of electrons in sections P and Q is denoted by vpand vQrespectively, then
Answer» A current I is passing through a wire having two sections P and Q of uniform diameters d and $\frac{d}{2}$ respectively. If the mean drift velocity of electrons in sections P and Q is denoted by $v_{p}$ and $v_{Q}$ respectively, then

Discussion

2126.	To a man running at the rate of 4 km/h, the rain appears to fall vertically. When he increases his speed to 8 km/h, rain appears coming to man at an angle of 45∘ with vertical. Find the magnitude of velocity of rain with respect to ground.
Answer» To a man running at the rate of $4 km/h$ , the rain appears to fall vertically. When he increases his speed to $8 km/h$ , rain appears coming to man at an angle of $45^{\circ}$ with vertical. Find the magnitude of velocity of rain with respect to ground.

Discussion

2127.	A parallel plate capacitor of area A, plate separation d and capacitance C is filled with three different dielectric materials having dielectric constants K1,K2 and K3 as shown in Fig. If a single dielectric material is to be used to have the same capacitance C in this capacitor, then its dielectric constant K is given by
Answer» A parallel plate capacitor of area A, plate separation d and capacitance C is filled with three different dielectric materials having dielectric constants $K_{1}, K_{2} a n d K_{3}$ as shown in Fig. If a single dielectric material is to be used to have the same capacitance C in this capacitor, then its dielectric constant K is given by

Discussion

2128.	A particle is released at point P(−2 m,2 m) on a smooth parabolic track given by y=x22. It slides down the track and leaves the contact with the track at point Q(1 m,0.5 m), and then slides till point R along QR. Distance QR in m equals (g=10 m/s2)
Answer» A particle is released at point $P (- 2 m, 2 m)$ on a smooth parabolic track given by $y = \frac{x^{2}}{2}$ . It slides down the track and leaves the contact with the track at point $Q (1 m, 0.5 m)$ , and then slides till point $R$ along $Q R$ . Distance $Q R$ in m equals $(g = 10 {m/s}^{2})$

Discussion

2129.	From a tower of height H, a particle is thrown vertically upwards with a speed u. The time taken by the particle to hit the ground is n times the time taken by it to reach the highest point of its path. The relation between H, u and n is
Answer» From a tower of height $H$ , a particle is thrown vertically upwards with a speed $u$ . The time taken by the particle to hit the ground is $n$ times the time taken by it to reach the highest point of its path. The relation between $H$ , $u$ and $n$ is

Discussion

2130.	A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of earth
Answer» A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of earth

Discussion

2131.	A thin brass rectangular sheet of sides 15.0 cm and 12.0 cm is heated in a furnace to 527∘C and taken out in vacuum. Find the electric power needed to maintain the sheet at this temperature, given that its emissivity is 0.250.(Take σ=5.67×10−8 W/m2− K4)
Answer» A thin brass rectangular sheet of sides $15.0 cm$ and $12.0 cm$ is heated in a furnace to $527^{\circ} C$ and taken out in vacuum. Find the electric power needed to maintain the sheet at this temperature, given that its emissivity is $0.250$ . (Take $σ = 5.67 \times 10^{- 8} {W/m}^{2} - K^{4}$ )

Discussion

2132.	A train has a speed of 60 km/h for the first one hour and 40 km/h for the next half hour. Its average speed in km/h is
Answer» A train has a speed of 60 km/h for the first one hour and 40 km/h for the next half hour. Its average speed in km/h is

2132.

A train has a speed of 60 km/h for the first one hour and 40 km/h for the next half hour. Its average speed in km/h is

Answer»

A train has a speed of 60 km/h for the first one hour and 40 km/h for the next half hour. Its average speed in km/h is

Discussion

2133.	A force →F=^i−3^j−5^k acts at a point →r=4^i+8^j+a^k from the origin. What should be the value of 'a' so that the resulting torque will be maximum? What is the magnitude of the resulting maximum torque?
Answer» A force $\to F =^i - 3^j - 5^k$ acts at a point $\to r = 4^i + 8^j + a^k$ from the origin. What should be the value of ' $a$ ' so that the resulting torque will be maximum? What is the magnitude of the resulting maximum torque?

Discussion

2134.	An astronomical telescope is to be designed to have a magnifying power of 50 in normal adjustment. If the length of the tube is 102 cm, find the powers of the objective and the eyepiece.
Answer» An astronomical telescope is to be designed to have a magnifying power of $50$ in normal adjustment. If the length of the tube is $102 c m$ , find the powers of the objective and the eyepiece.

Discussion

2135.	A uniform conducting rectangular loop of sides l, b and mass m carrying current i is hanging horizontally with the help of two vertical strings. There exists a uniform horizontal magnetic field B which is parallel to the longer side of the loop. The value of tension which is least is
Answer» A uniform conducting rectangular loop of sides $l$ , $b$ and mass $m$ carrying current $i$ is hanging horizontally with the help of two vertical strings. There exists a uniform horizontal magnetic field B which is parallel to the longer side of the loop. The value of tension which is least is

Discussion

2136.	A body of mass m1 moving at a constant speed undergoes an elastic collision with a body of mass m2 initially at rest., the ratio of the kinetic energies of masses m2 and m1 after the collision is
Answer» A body of mass $m_{1}$ moving at a constant speed undergoes an elastic collision with a body of mass $m_{2}$ initially at rest., the ratio of the kinetic energies of masses $m_{2}$ and $m_{1}$ after the collision is

Discussion

2137.	While playing with the Crook’s tube, what was Mr. Roentgen looking for ?
Answer» While playing with the Crook’s tube, what was Mr. Roentgen looking for ?

Discussion

2138.	A puck of mass 100 gm is tied to a string and allowed to revolve in a horizontal circle of radius 2 cm on a frictionless horizontal table as shown in the figure. Other end of the string passes through a small hole at the centre of the table and a load of mass 5 kg is tied to the string. The suspended load remains in equilibrium while the puck revolves on the table. If the tension in the string is x (N) and speed of the puck is y (cm/s), then find the values of x and y respectively. Take g=10 m/s2.
Answer» A puck of mass $100 gm$ is tied to a string and allowed to revolve in a horizontal circle of radius $2 cm$ on a frictionless horizontal table as shown in the figure. Other end of the string passes through a small hole at the centre of the table and a load of mass $5 kg$ is tied to the string. The suspended load remains in equilibrium while the puck revolves on the table. If the tension in the string is $x (N)$ and speed of the puck is $y (cm/s)$ , then find the values of $x$ and $y$ respectively. Take $g = 10 {m/s}^{2}$ .

Discussion

2139.	A disc rotates about its axis with a constant angular acceleration of 4 rads2. Radial acceleration of a particle at a distance of 1 cm from the axis at the end of 1 sec is.
Answer» A disc rotates about its axis with a constant angular acceleration of $4 \frac{r a d}{s^{2}} .$ Radial acceleration of a particle at a distance of $1 c m$ from the axis at the end of $1 s e c$ is.

Discussion

2140.	System is shown in the figure and man is pulling the rope from both sides with constant speed ‘u′. Then what will be the velocity of the block, if the rope is inextensible?
Answer» System is shown in the figure and man is pulling the rope from both sides with constant speed $‘ u^{'}$ . Then what will be the velocity of the block, if the rope is inextensible?

Discussion

2141.	A body of mass 0.05 kg travelling with a velocity of 5 m/s make angle of 300 with the wall as shown. The body rebounds with the same speed making an angle of 300 with the wall. Find the change in momentum of the body.
Answer» A body of mass $0.05 k g$ travelling with a velocity of $5 m / s$ make angle of $30^{0}$ with the wall as shown. The body rebounds with the same speed making an angle of $30^{0}$ with the wall. Find the change in momentum of the body.

Discussion

2142.	A particle of mass m is executing uniform circular motion on a path of radius r. If p is the magnitude of its linear momentum. The radial force acting on the particle is
Answer» A particle of mass m is executing uniform circular motion on a path of radius r. If p is the magnitude of its linear momentum. The radial force acting on the particle is

Discussion

2143.	Twelve identical resistance are arranged to form a cubical structure find the effective resistance between .1 and 8
Answer» Twelve identical resistance are arranged to form a cubical structure find the effective resistance between . 1 and 8

Discussion

2144.	Two blocks m1=5 gm and m2=10 gm are hung vertically over a light frictionless pulley as shown here. What is the acceleration of the masses when they are left free?(where g is acceleration due to gravity)
Answer» Two blocks $m_{1} = 5 gm$ and $m_{2} = 10 gm$ are hung vertically over a light frictionless pulley as shown here. What is the acceleration of the masses when they are left free? (where $g$ is acceleration due to gravity)

Discussion

2145.	If the distance between centers of earth and moon is D and the mass of earth is 81 times the mass of moon, then at what distance from centre of earth the gravitational force will be zero
Answer» If the distance between centers of earth and moon is D and the mass of earth is 81 times the mass of moon, then at what distance from centre of earth the gravitational force will be zero

Discussion

2146.	When a belt moves horizontally at a constant speed of 1.5 ms−1, gravels are falling on it at rate of 5 kg s−1. Then, the extra power required to drive the belt is
Answer» When a belt moves horizontally at a constant speed of $1.5 {ms}^{- 1},$ gravels are falling on it at rate of $5$ ${kg s}^{- 1} .$ Then, the extra power required to drive the belt is

Discussion

2147.	Sodium has a work function of 2.28 eV. Let's say, I introduce a very strong external electric field, which is applying a force on the electrons outwards, thus giving them electrical potential energy of 1.5 eV each. What is the work function of the metal surface in such a case?
Answer» Sodium has a work function of 2.28 eV. Let's say, I introduce a very strong external electric field, which is applying a force on the electrons outwards, thus giving them electrical potential energy of 1.5 eV each. What is the work function of the metal surface in such a case?

Discussion

2148.	Derivative of f(x)=4ex−4x+2lnx is
Answer» Derivative of $f (x) = 4 e^{x} - 4^{x} + 2 ln x$ is

Discussion

2149.	A block of mass 1 kg is at rest relative to a smooth wedge moving leftwards with constant acceleration a=5 m/s2Let N be the normal reaction between the block and the wedge. Then (g=10 m/s2)
Answer» A block of mass $1 kg$ is at rest relative to a smooth wedge moving leftwards with constant acceleration $a = 5 {m/s}^{2}$ Let $N$ be the normal reaction between the block and the wedge. Then $(g = 10 {m/s}^{2})$

Discussion

2150.	A fan is revolving with an angular speed of 120 rpm. Suddenly a boy switches off the fan and it eventually comes to rest by making 30 revolutions in 2 mins. The average angular velocity of the fan is
Answer» A fan is revolving with an angular speed of $120 rpm$ . Suddenly a boy switches off the fan and it eventually comes to rest by making 30 revolutions in 2 mins. The average angular velocity of the fan is

Discussion

Explore topic-wise InterviewSolutions in .

A force F=(^i+4^j) N acts on the block shown. The force of friction acting on the block is :

In the arrangement shown in figure, pulleys are small and light and the springs are ideal. K1=25π2Nm,K2=2K1,K3=3K1 and K4=4K1 are the force constants of the springs. Calculate the period of small vertical oscillations (in s) of the block of mass m=3 kg

The power radiated by a black body is P and it radiates maximum energy around the wavelength λ0. If the temperature of the black body is now changed so that it radiates maximum energy around wavelength 3λ04, the power radiated by it will increase by a factor of

The electric potential varies in space according to the relation V=3x+4y. A particle of mass 0.1kg starts from rest from point (2,3.2) under the influence of this field. The charge on the particle is +1μC. Assume V and (x,y) are in S.I. unitsThe time taken to cross the x - axis is

A car sometimes overturns while taking a turn. When it overturns, it is

A boat takes t1 time while going downstream between two fixed points A and B, and takes t2 time while going upstream through the same distance. If river does not flow, then the time taken by the boat to cover the same distance is

Considering the points lying on a straight line joining two fixed charges with equal magnitude and opposite nature, between the charges there is

If an incident ray is directed towards a corner reflector as shown, at what angle(θ) does the reflected ray emerge?

A body of mass 'm' moving with velocity 'v' collides head on elastically with another body of mass '2m' which was initially at rest. The ratio of K.E. of colliding body of mass 'm' before and after collision would be

The engine of a train sounds a whistle at frequency (f). The frequency heard by a passenger is

In the figure shown below, ma=3 kg and mb=1 kg. String is inextensible and light. Find the acceleration of centre of mass of the system.

From the following displacement-time graph find out the velocity of a moving body

A long horizontally fixed wire carries a current of 100A. Directly above and parallel to it is another wire carrying a current of 20 A and weighing 0.04 N m-1 . What should be the separation between the two wires so that the upper wire is just supported by magnetic repulsion?

A square frame is made using four thin uniform rods of length l each having linear mass densities λ, 2λ, 3λ and 4λ as shown in the figure. Which of the following is correct?

A small block is shot into each of the four tracks as shown in the options. Each of the tracks rises to the same height. The speed with which the block enters the track is the same in all cases. At the highest point of the track, the normal reaction is maximum in -

A flexible wire bent in the form of a circle is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in the figure.The graph of magnitude of induced emf in the coil is represented by

A loop ABCDEFA of straight edges has six corner points A(0,0,0), B(5,0,0), C(5,5,0), D(0,5,0), E(0,5,5), F(0,0,5). The magnetic field in this region is →B = (3^i+4^k) T. The quantity of flux through the loop ABCDEFA (in Wb) is

A planet has mass 110 of that of earth, while radius is 13 that of earth. If a person can throw a stone on earth surface to a height of 90m, then he will be able to throw the stone on that planet to a height

A conductor ABOCD moves along its bisector with a velocity 1 m/s through a perpendicular magnetic field of 1 Wb/m2, as shown in figure. If all the four sides are of 1 m length each, then the induced emf between A and D (in volts) is approximately (upto two decimals)

A current I is passing through a wire having two sections P and Q of uniform diameters d and d2 respectively. If the mean drift velocity of electrons in sections P and Q is denoted by vpand vQrespectively, then

To a man running at the rate of 4 km/h, the rain appears to fall vertically. When he increases his speed to 8 km/h, rain appears coming to man at an angle of 45∘ with vertical. Find the magnitude of velocity of rain with respect to ground.

A particle is released at point P(−2 m,2 m) on a smooth parabolic track given by y=x22. It slides down the track and leaves the contact with the track at point Q(1 m,0.5 m), and then slides till point R along QR. Distance QR in m equals (g=10 m/s2)

From a tower of height H, a particle is thrown vertically upwards with a speed u. The time taken by the particle to hit the ground is n times the time taken by it to reach the highest point of its path. The relation between H, u and n is

A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of earth

A thin brass rectangular sheet of sides 15.0 cm and 12.0 cm is heated in a furnace to 527∘C and taken out in vacuum. Find the electric power needed to maintain the sheet at this temperature, given that its emissivity is 0.250.(Take σ=5.67×10−8 W/m2− K4)

A train has a speed of 60 km/h for the first one hour and 40 km/h for the next half hour. Its average speed in km/h is

A force →F=^i−3^j−5^k acts at a point →r=4^i+8^j+a^k from the origin. What should be the value of 'a' so that the resulting torque will be maximum? What is the magnitude of the resulting maximum torque?

An astronomical telescope is to be designed to have a magnifying power of 50 in normal adjustment. If the length of the tube is 102 cm, find the powers of the objective and the eyepiece.

A uniform conducting rectangular loop of sides l, b and mass m carrying current i is hanging horizontally with the help of two vertical strings. There exists a uniform horizontal magnetic field B which is parallel to the longer side of the loop. The value of tension which is least is

A body of mass m1 moving at a constant speed undergoes an elastic collision with a body of mass m2 initially at rest., the ratio of the kinetic energies of masses m2 and m1 after the collision is

While playing with the Crook’s tube, what was Mr. Roentgen looking for ?

A disc rotates about its axis with a constant angular acceleration of 4 rads2. Radial acceleration of a particle at a distance of 1 cm from the axis at the end of 1 sec is.

System is shown in the figure and man is pulling the rope from both sides with constant speed ‘u′. Then what will be the velocity of the block, if the rope is inextensible?

A body of mass 0.05 kg travelling with a velocity of 5 m/s make angle of 300 with the wall as shown. The body rebounds with the same speed making an angle of 300 with the wall. Find the change in momentum of the body.

A particle of mass m is executing uniform circular motion on a path of radius r. If p is the magnitude of its linear momentum. The radial force acting on the particle is

Twelve identical resistance are arranged to form a cubical structure find the effective resistance between .1 and 8

Two blocks m1=5 gm and m2=10 gm are hung vertically over a light frictionless pulley as shown here. What is the acceleration of the masses when they are left free?(where g is acceleration due to gravity)

If the distance between centers of earth and moon is D and the mass of earth is 81 times the mass of moon, then at what distance from centre of earth the gravitational force will be zero

When a belt moves horizontally at a constant speed of 1.5 ms−1, gravels are falling on it at rate of 5 kg s−1. Then, the extra power required to drive the belt is

Sodium has a work function of 2.28 eV. Let's say, I introduce a very strong external electric field, which is applying a force on the electrons outwards, thus giving them electrical potential energy of 1.5 eV each. What is the work function of the metal surface in such a case?

Derivative of f(x)=4ex−4x+2lnx is

A block of mass 1 kg is at rest relative to a smooth wedge moving leftwards with constant acceleration a=5 m/s2Let N be the normal reaction between the block and the wedge. Then (g=10 m/s2)

A fan is revolving with an angular speed of 120 rpm. Suddenly a boy switches off the fan and it eventually comes to rest by making 30 revolutions in 2 mins. The average angular velocity of the fan is