50278 + Interview Questions in Physics

1.	A sounding body emitting a frequency of 150 Hz is dropped from a height. During its fall under gravity it crosses a balloon moving upwards with a constant velocity of 2 m/s, after one second when it started to fall. The difference in the frequency observed by the man in balloon just before and just after crossing the body will be(in Hz) (Take velocity of sound as 300 m/s and g=10 m/s2)
Answer» A sounding body emitting a frequency of 150 Hz is dropped from a height. During its fall under gravity it crosses a balloon moving upwards with a constant velocity of 2 m/s, after one second when it started to fall. The difference in the frequency observed by the man in balloon just before and just after crossing the body will be(in Hz) (Take velocity of sound as 300 m/s and g=10 $m / s^{2}$ )

Discussion

2.	A ball is thrown upwards from the foot of a tower. The ball crosses the top of the tower twice after an interval of 4 second and the ball reaches ground after 8 seconds, then the height of tower in meters is 12×x. Then, find the value of x.
Answer» A ball is thrown upwards from the foot of a tower. The ball crosses the top of the tower twice after an interval of $4$ second and the ball reaches ground after $8$ seconds, then the height of tower in meters is $12 \times x$ . Then, find the value of $x$ .

Discussion

3.	A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is
Answer» A filament bulb ( $500 W, 100 V$ ) is to be used in a $230 V$ main supply. When a resistance $R$ is connected in series, it works perfectly and the bulb consumes $500 W$ . The value of $R$ is

Discussion

4.	The frequencies (f) of Kα lines of different material (z) are plotted on a graph as shown in figure. Choose the correct variation which satisfies the Moseley's law
Answer» The frequencies $(f)$ of $K_{α}$ lines of different material $(z)$ are plotted on a graph as shown in figure. Choose the correct variation which satisfies the Moseley's law

Discussion

5.	Two blocks (m and M) are arranged as shown. There is friction between ground and M only and other surfaces are frictionless. The coefficient of friction between M and ground is 0.25. Find the maximum ratio of m and M i.e. (m/M) so that the system remains at rest
Answer» Two blocks ( $m$ and $M$ ) are arranged as shown. There is friction between ground and $M$ only and other surfaces are frictionless. The coefficient of friction between $M$ and ground is $0.25$ . Find the maximum ratio of $m$ and $M i.e. (m / M)$ so that the system remains at rest

Discussion

6.	If →A=^i+2^j−^k and →B=2^i+3^j+4^k, Then the vector which is perpendicular to both vectors →A and →B is
Answer» If $\to A =^i + 2^j -^k$ and $\to B = 2^i + 3^j + 4^k$ , Then the vector which is perpendicular to both vectors $\to A$ and $\to B$ is

Discussion

7.	An inductor of inductance L = 400 mH and resistors of resistance R1=2Ω and R2=2Ω are connected to a battery of emf 12 V as shown in the figure. The internal resistance of the battery is negligible. The switch S is closed at t = 0. The potential drop across L as a function of time is
Answer» An inductor of inductance L = 400 mH and resistors of resistance $R_{1} = 2 Ω$ and $R_{2} = 2 Ω$ are connected to a battery of emf 12 V as shown in the figure. The internal resistance of the battery is negligible. The switch S is closed at t = 0. The potential drop across L as a function of time is

Discussion

8.	The external and internal diameters of a hollow cylinder are measured to be (4.23 ± 0.01) cm and (3.89 ± 0.01)cm. The thickness of the wall of the cylinder is
Answer» The external and internal diameters of a hollow cylinder are measured to be (4.23 $\pm$ 0.01) cm and (3.89 $\pm$ 0.01)cm. The thickness of the wall of the cylinder is

Discussion

9.	A block A of mass 200 kg rests on a block B of mass 300 kg. A is tied with a horizontal string to a wall. Coefficient of friction between A and B is 0.25 and that between B and floor is 0.2. The horizontal force F needed to move the block B is (g=10 ms−2).
Answer» A block A of mass 200 kg rests on a block B of mass 300 kg. A is tied with a horizontal string to a wall. Coefficient of friction between A and B is 0.25 and that between B and floor is 0.2. The horizontal force F needed to move the block B is $(g = 10 m s^{- 2})$ .

9.

A block A of mass 200 kg rests on a block B of mass 300 kg. A is tied with a horizontal string to a wall. Coefficient of friction between A and B is 0.25 and that between B and floor is 0.2. The horizontal force F needed to move the block B is (g=10 ms−2).

Answer»

A block A of mass 200 kg rests on a block B of mass 300 kg. A is tied with a horizontal string to a wall. Coefficient of friction between A and B is 0.25 and that between B and floor is 0.2. The horizontal force F needed to move the block B is $(g = 10 m s^{- 2})$ .

Discussion

10.	A regular hexagonal lamina of side a made up of perfectly absorbing material is kept in a region where a parallel beam of light with intensity I having a large aperture falls on it. If the normal to the surface of the hexagon makes an angle of 30∘ with the beam then the force experienced by the hexagon will be
Answer» A regular hexagonal lamina of side a made up of perfectly absorbing material is kept in a region where a parallel beam of light with intensity I having a large aperture falls on it. If the normal to the surface of the hexagon makes an angle of $30^{\circ}$ with the beam then the force experienced by the hexagon will be

Discussion

11.	If dimensions of length are expressed as Gxcyhz where G, c and h are universal gravitational constants, speed of light and Planck's constant respectively then:
Answer» If dimensions of length are expressed as $G^{x} c^{y} h^{z}$ where G, c and h are universal gravitational constants, speed of light and Planck's constant respectively then:

Discussion

12.	A box P and a coil Q are connected in series with an ac source of variable frequency. The emf of the source is constant at 10 V. Box P contains a capacitance of 1 μF in series with a resistance of 32 Ω. Coil Q has a self inductance of 4.9 mH and a resistance of 68 Ω in series. The frequency is adjusted so that maximum current flows in P and Q. The impedance of Q at this frequency is
Answer» A box P and a coil Q are connected in series with an ac source of variable frequency. The emf of the source is constant at $10 V$ . Box P contains a capacitance of $1 μ F$ in series with a resistance of $32 Ω$ . Coil Q has a self inductance of 4.9 mH and a resistance of $68 Ω$ in series. The frequency is adjusted so that maximum current flows in P and Q. The impedance of Q at this frequency is

Discussion

13.	Find the moment of inertia of uniform circular disc placed on the horizontal surface having origin as center. If the moment of inertia of disc along the axis passing through the the diameter is 2 kg m2, find the moment of inertia of disc about the axis perpendicular to the plane of disc and passing through its centre.
Answer» Find the moment of inertia of uniform circular disc placed on the horizontal surface having origin as center. If the moment of inertia of disc along the axis passing through the the diameter is $2 {kg m}^{2}$ , find the moment of inertia of disc about the axis perpendicular to the plane of disc and passing through its centre.

Discussion

14.	Can the coefficient of friction be more than one?
Answer» Can the coefficient of friction be more than one?

Discussion

15.	Average velocity of a particle moving in a straight line, with constant acceleration ‘a’ and initial velocity 'u' in first 't' seconds is :
Answer» Average velocity of a particle moving in a straight line, with constant acceleration ‘a’ and initial velocity 'u' in first 't' seconds is :

Discussion

16.	Figure shows a block of mass m placed on a horizontal surface. The coefficient of static friction between the block and the surface is μ. The maximum force F that can be applied at point O such that the block does not slip on the surface is
Answer» Figure shows a block of mass $m$ placed on a horizontal surface. The coefficient of static friction between the block and the surface is $μ$ . The maximum force $F$ that can be applied at point $O$ such that the block does not slip on the surface is

Discussion

17.	An insect of mass m crawls along the hanging thread with an acceleration a =g2. The normal reaction offered by ground on the block of mass 2m kept stationary on ground is
Answer» An insect of mass m crawls along the hanging thread with an acceleration a = $\frac{g}{2}$ . The normal reaction offered by ground on the block of mass 2m kept stationary on ground is

17.

An insect of mass m crawls along the hanging thread with an acceleration a =g2. The normal reaction offered by ground on the block of mass 2m kept stationary on ground is

Answer»

An insect of mass m crawls along the hanging thread with an acceleration a = $\frac{g}{2}$ . The normal reaction offered by ground on the block of mass 2m kept stationary on ground is

Discussion

18.	The vector having magnitude equal to 5 and perpendicular to the vector →B=2^i−3^j+2^k and making equal angle with the positive X-axis and the positive Y-axis is
Answer» The vector having magnitude equal to $5$ and perpendicular to the vector $\to B = 2^i - 3^j + 2^k$ and making equal angle with the positive $X$ -axis and the positive $Y$ -axis is

Discussion

19.	A uniform solid sphere of radius R has a cavity of radius 1 m cut from it. If the centre of mass of the system lies at the periphery of the cavity, then:
Answer» A uniform solid sphere of radius $R$ has a cavity of radius $1 m$ cut from it. If the centre of mass of the system lies at the periphery of the cavity, then:

Discussion

20.	A rod is measured using a scale. The reading is 60 cm at 12∘C. If thermal coefficient of linear expansion of the rod is 3×10−5/∘C, the reading of the rod at 42∘C is: (Assume the scale does not expand)
Answer» A rod is measured using a scale. The reading is $60 cm$ at $12^{\circ} C$ . If thermal coefficient of linear expansion of the rod is $3 \times 10^{- 5} /^{\circ} C$ , the reading of the rod at $42^{\circ} C$ is: (Assume the scale does not expand)

Discussion

21.	A power P=2t3 is applied to the particle. If the kinetic energy of the particle is K and velocity is v then
Answer» A power $P = 2 t^{3}$ is applied to the particle. If the kinetic energy of the particle is $K$ and velocity is $v$ then

Discussion

22.	Comment on the corrections of the following two statements based on the given situation. Consider a line of length ‘l’ and uniform charge density λ. Assume a Gaussian surface S, a cylinder of radius R and height h. Statement 1: φ=flux through S=λHϵ0 Statement 2: \|→E\|at all the points on its curved surface=λϵ02πR
Answer» Comment on the corrections of the following two statements based on the given situation. Consider a line of length ‘l’ and uniform charge density $λ$ . Assume a Gaussian surface S, a cylinder of radius R and height h. Statement 1: $φ = f l u x t h r o u g h S = \frac{λ H}{ϵ_{0}}$ Statement 2: $\| \to E \| a t a l l t h e p o i n t s o n i t s c u r v e d s u r f a c e = \frac{λ}{ϵ_{0} 2 π R}$

22.

Comment on the corrections of the following two statements based on the given situation. Consider a line of length ‘l’ and uniform charge density λ. Assume a Gaussian surface S, a cylinder of radius R and height h. Statement 1: φ=flux through S=λHϵ0 Statement 2: |→E|at all the points on its curved surface=λϵ02πR

Answer»

Comment on the corrections of the following two statements based on the given situation.

Consider a line of length ‘l’ and uniform charge density $λ$ . Assume a Gaussian surface S, a cylinder of radius R and height h.

Statement 1: $φ = f l u x t h r o u g h S = \frac{λ H}{ϵ_{0}}$

Statement 2: $| \to E | a t a l l t h e p o i n t s o n i t s c u r v e d s u r f a c e = \frac{λ}{ϵ_{0} 2 π R}$

Discussion

23.	A wheel makes 360 revolutions in one minute. Through how many radians does it turn in one second?
Answer» A wheel makes 360 revolutions in one minute. Through how many radians does it turn in one second?

Discussion

24.	Two small spheres each having the charge +Q are suspended by insulating threads of length L from a hook. This arrangement is taken in space where there is no gravitational effect. Then the angle between the two threads at the point of suspension and the tension in each thread will be
Answer» Two small spheres each having the charge $+ Q$ are suspended by insulating threads of length $L$ from a hook. This arrangement is taken in space where there is no gravitational effect. Then the angle between the two threads at the point of suspension and the tension in each thread will be

Discussion

25.	The elevator starts from the ground floor and goes up to the 4th floor it drops a person and comes down to the first floor then displacement in both the cases are?
Answer» The elevator starts from the ground floor and goes up to the 4th floor it drops a person and comes down to the first floor then displacement in both the cases are?

Discussion

26.	The engine of a motorcycle can produce a max acc. of 5 mtr per sec square. Its brakes can produce a maximum retardation of 10 mtr per sec square. What is the min time in which it can cover a distance of 1.5km.?
Answer» The engine of a motorcycle can produce a max acc. of 5 mtr per sec square. Its brakes can produce a maximum retardation of 10 mtr per sec square. What is the min time in which it can cover a distance of 1.5km.?

Discussion

27.	In the circuit shown in the following figure E=10 V,R1=2 ohm,R2=3 ohm and R3=6 ohm and L=5 henry . The current I1 just after pressing the switch S is (correct answer + 2, wrong answer - 0.50)
Answer» In the circuit shown in the following figure $E = 10 V, R_{1} = 2 ohm, R_{2} = 3 ohm$ and $R_{3} = 6 ohm$ and $L = 5 henry$ . The current $I_{1}$ just after pressing the switch $S$ is (correct answer + 2, wrong answer - 0.50)

Discussion

28.	The number of particles crossing the unit area perpendicular to the x –axis per unit time, is given by:N=−D(n2−n1x2−x1)Wheren1 and n2are the numbers of particles per unit volume for the values of x meant to be x1 and x2 respectively. What is the dimensional formula for the diffusion constant D?
Answer» The number of particles crossing the unit area perpendicular to the x –axis per unit time, is given by: $N = - D (\frac{n_{2} - n_{1}}{x_{2} - x_{1}})$ Where $n_{1}$ and $n_{2}$ are the numbers of particles per unit volume for the values of x meant to be $x_{1}$ and $x_{2}$ respectively. What is the dimensional formula for the diffusion constant D?

28.

The number of particles crossing the unit area perpendicular to the x –axis per unit time, is given by:N=−D(n2−n1x2−x1)Wheren1 and n2are the numbers of particles per unit volume for the values of x meant to be x1 and x2 respectively. What is the dimensional formula for the diffusion constant D?

Answer»

The number of particles crossing the unit area perpendicular to the x –axis per unit time, is given by:

$N = - D (\frac{n_{2} - n_{1}}{x_{2} - x_{1}})$

Where

$n_{1}$ and $n_{2}$

are the numbers of particles per unit volume for the values of x meant to be $x_{1}$ and $x_{2}$ respectively. What is the dimensional formula for the diffusion constant D?

Discussion

29.	At t=0 a projectile is fired from a point O (taken as origin) on the ground with a speed of 50 m/s at an angle of 53∘ with the horizontal. It just passes two points A and B each at height 75 m above horizontal as shown. The horizontal separation between the points A and B is (Take g=10 m/s2)
Answer» At $t = 0$ a projectile is fired from a point $O$ (taken as origin) on the ground with a speed of $50 m /$ s at an angle of $53^{\circ}$ with the horizontal. It just passes two points $A$ and $B$ each at height $75 m$ above horizontal as shown. The horizontal separation between the points $A$ and $B$ is (Take $g = 10 m / s^{2}$ )

Discussion

30.	can moment of inertia of an body be defined about a point (that is not an axis)
Answer» can moment of inertia of an body be defined about a point (that is not an axis)

Discussion

31.	One end of a massless spring of spring constant k=200 N/m and natural length 0.5 m is fixed at the centre of a frictionless horizontal table. The other end is connected to a load of mass 1 kg lying on the table at rest. If the spring remains horizontal and mass is made to rotate at an angular speed of 2 rad/s, find the elongation in the spring.
Answer» One end of a massless spring of spring constant $k = 200 N/m$ and natural length $0.5 m$ is fixed at the centre of a frictionless horizontal table. The other end is connected to a load of mass $1 kg$ lying on the table at rest. If the spring remains horizontal and mass is made to rotate at an angular speed of $2 rad/s$ , find the elongation in the spring.

Discussion

32.	An alternating emf is applied across a parallel combination of a resistance R, capacitance C and an inductance L. If IR,IL,IC are the currents through R,L and C respectively, then the diagram which correctly represents, the phase relationship among IR,IL,IC and source emf E, is given by
Answer» An alternating emf is applied across a parallel combination of a resistance $R$ , capacitance $C$ and an inductance $L$ . If $I_{R}, I_{L}, I_{C}$ are the currents through $R, L$ and $C$ respectively, then the diagram which correctly represents, the phase relationship among $I_{R}, I_{L}, I_{C}$ and source emf $E$ , is given by

Discussion

33.	What would happen in the context of charging by induction if instead of bring a charged and an uncharged body close to each other we bring two charged bodies close to each other?
Answer» What would happen in the context of charging by induction if instead of bring a charged and an uncharged body close to each other we bring two charged bodies close to each other?

Discussion

34.	The kinetic energy of 1 mole of oxygen molecules in cal mol−1 at 27∘C is__.
Answer» The kinetic energy of 1 mole of oxygen molecules in $c a l m o l^{- 1}$ at $27^{\circ} C$ is__.

Discussion

35.	Why Earth behave like a magnet? Explain magnetic elements of earth at a place giving expressions.
Answer» Why Earth behave like a magnet? Explain magnetic elements of earth at a place giving expressions.

Discussion

36.	An iron nail is dropped from a height h from the level of a sand bed. If it penetrates through a distance x in the sand before coming to rest, the average force exerted by the sand on the nail is,
Answer» An iron nail is dropped from a height h from the level of a sand bed. If it penetrates through a distance x in the sand before coming to rest, the average force exerted by the sand on the nail is,

Discussion

37.	I'm not understanding about the topic fundamental and derived units.
Answer» I'm not understanding about the topic fundamental and derived units.

Discussion

38.	When iron(rod) is in solid form then how it's molecules are in gaseous state ?
Answer» When iron(rod) is in solid form then how it's molecules are in gaseous state ?

Discussion

39.	A solid sphere and a disc are released from the top of an inclined plane such that both are rolling with slipping if ts and td are their respective time of journey to the bottom of plain then prove that ts= td
Answer» A solid sphere and a disc are released from the top of an inclined plane such that both are rolling with slipping if t_s and t_d are their respective time of journey to the bottom of plain then prove that t_s= t_d

Discussion

40.	A truck is moving at 5 m/s infront of a car, moving at 10 m/s. To overtake, car blows a horn of frequency 200 Hz. Find the frequency of horn that the car driver listens due to the reflection of sound from the truck. Here, wind is also blowing at 5 m/s, opposite to the direction of motion of both the car and the truck. Take the speed of sound as 330 m/s.
Answer» A truck is moving at 5 m/s infront of a car, moving at 10 m/s. To overtake, car blows a horn of frequency 200 Hz. Find the frequency of horn that the car driver listens due to the reflection of sound from the truck. Here, wind is also blowing at 5 m/s, opposite to the direction of motion of both the car and the truck. Take the speed of sound as 330 m/s.

Discussion

41.	I I could not understand how to derive an derivative by integration as well as differentiations so please tell me how to derive and derivative using integration and differentiation
Answer» I I could not understand how to derive an derivative by integration as well as differentiations so please tell me how to derive and derivative using integration and differentiation

Discussion

42.	The moment of inertia of a circular ring about an axis passing through its center and normal to its plane is 200 gm−cm2. Then its moment of inertia about a diameter is
Answer» The moment of inertia of a circular ring about an axis passing through its center and normal to its plane is $200 g m - c m^{2}$ . Then its moment of inertia about a diameter is

Discussion

43.	Can superconductors exhibit resonance ? Why or why not ?
Answer» Can superconductors exhibit resonance ? Why or why not ?

Discussion

44.	A cylindrical tank having cross-sectional area A = 0.5 m2 is filled with two liquids of density ρ1 = 900 kg m−3 and ρ2 = 600 kg m−3, to a height h = 60 cm each as shown in figure. A small hole having area a = 5 cm2 is made in right vertical wall at a height y = 20 cm from the bottom. A horizontal force F is applied on the tank to keep it in static equilibrium. The tank is lying on a horizontal surface. Neglect mass of cylindrical tank comparison to mass of liquids. Horizontal force F to keep the cylinder in static equilibrium, if it is placed on a smooth horizontal plane
Answer» A cylindrical tank having cross-sectional area A = 0.5 $m^{2}$ is filled with two liquids of density $ρ_{1}$ = 900 kg $m^{- 3}$ and $ρ_{2}$ = 600 kg $m^{- 3}$ , to a height h = 60 cm each as shown in figure. A small hole having area a = 5 $c m^{2}$ is made in right vertical wall at a height y = 20 cm from the bottom. A horizontal force F is applied on the tank to keep it in static equilibrium. The tank is lying on a horizontal surface. Neglect mass of cylindrical tank comparison to mass of liquids. Horizontal force F to keep the cylinder in static equilibrium, if it is placed on a smooth horizontal plane

44.

A cylindrical tank having cross-sectional area A = 0.5 m2 is filled with two liquids of density ρ1 = 900 kg m−3 and ρ2 = 600 kg m−3, to a height h = 60 cm each as shown in figure. A small hole having area a = 5 cm2 is made in right vertical wall at a height y = 20 cm from the bottom. A horizontal force F is applied on the tank to keep it in static equilibrium. The tank is lying on a horizontal surface. Neglect mass of cylindrical tank comparison to mass of liquids. Horizontal force F to keep the cylinder in static equilibrium, if it is placed on a smooth horizontal plane

Answer»

A cylindrical tank having cross-sectional area A = 0.5 $m^{2}$ is filled with two liquids of density $ρ_{1}$ = 900 kg $m^{- 3}$ and $ρ_{2}$ = 600 kg $m^{- 3}$ , to a height h = 60 cm each as shown in figure. A small hole having area a = 5 $c m^{2}$ is made in right vertical wall at a height y = 20 cm from the bottom. A horizontal force F is applied on the tank to keep it in static equilibrium. The tank is lying on a horizontal surface. Neglect mass of cylindrical tank comparison to mass of liquids. Horizontal force F to keep the cylinder in static equilibrium, if it is placed on a smooth horizontal plane

Discussion

45.	A vessel contains 1 mole of O2 gas (molar mass 32) at a temperature T. The pressure of the gas is P. An identical vessel containing one mole of He gas (molar mass 4) at a temperature 2T has a pressure of
Answer» A vessel contains $1$ mole of $O_{2}$ gas (molar mass $32$ ) at a temperature $T$ . The pressure of the gas is $P$ . An identical vessel containing one mole of $H e$ gas (molar mass $4$ ) at a temperature $2 T$ has a pressure of

Discussion

46.	A rod of mass ′M′ and length ′L′ lies on horizontal table and hinged at its one end. A particle of mass ′m′ is moving with velocity ′v′ and it hits perpendicularly to other end of the rod. If particles sticks to the rod after collision, then find the angular velocity of the rod.
Answer» A rod of mass $^{'} M^{'}$ and length $^{'} L^{'}$ lies on horizontal table and hinged at its one end. A particle of mass $^{'} m^{'}$ is moving with velocity $^{'} v^{'}$ and it hits perpendicularly to other end of the rod. If particles sticks to the rod after collision, then find the angular velocity of the rod.

Discussion

47.	A stone dropped from a certain height reaches ground in 5 sec. If it is dropped and stopped for infinitesimal time interval at t=3 s, then time taken by the stone to reach the ground is
Answer» A stone dropped from a certain height reaches ground in $5 sec$ . If it is dropped and stopped for infinitesimal time interval at $t = 3 s$ , then time taken by the stone to reach the ground is

Discussion

48.	z¯¯¯z = 0 if and only if:
Answer» z $¯ ¯ ¯ z$ = 0 if and only if:

Discussion

49.	Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k is T when block is uncharged. If a charge q is given to the block then, the new time period of oscillation will be
Answer» Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k is T when block is uncharged. If a charge q is given to the block then, the new time period of oscillation will be

49.

Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k is T when block is uncharged. If a charge q is given to the block then, the new time period of oscillation will be

Answer»

Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k is T when block is uncharged. If a charge q is given to the block then, the new time period of oscillation will be

Discussion

50.	Two terminals of a cell of emf 2.5 V are connected to the two ends of the 10 ohm resistance coil. If the current in the circuit is 0.2 A, then the internal resistance of the cell is
Answer» Two terminals of a cell of emf 2.5 V are connected to the two ends of the 10 ohm resistance coil. If the current in the circuit is 0.2 A, then the internal resistance of the cell is

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A ball is thrown upwards from the foot of a tower. The ball crosses the top of the tower twice after an interval of 4 second and the ball reaches ground after 8 seconds, then the height of tower in meters is 12×x. Then, find the value of x.

A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is

The frequencies (f) of Kα lines of different material (z) are plotted on a graph as shown in figure. Choose the correct variation which satisfies the Moseley's law

Two blocks (m and M) are arranged as shown. There is friction between ground and M only and other surfaces are frictionless. The coefficient of friction between M and ground is 0.25. Find the maximum ratio of m and M i.e. (m/M) so that the system remains at rest

If →A=^i+2^j−^k and →B=2^i+3^j+4^k, Then the vector which is perpendicular to both vectors →A and →B is

An inductor of inductance L = 400 mH and resistors of resistance R1=2Ω and R2=2Ω are connected to a battery of emf 12 V as shown in the figure. The internal resistance of the battery is negligible. The switch S is closed at t = 0. The potential drop across L as a function of time is

The external and internal diameters of a hollow cylinder are measured to be (4.23 ± 0.01) cm and (3.89 ± 0.01)cm. The thickness of the wall of the cylinder is

A block A of mass 200 kg rests on a block B of mass 300 kg. A is tied with a horizontal string to a wall. Coefficient of friction between A and B is 0.25 and that between B and floor is 0.2. The horizontal force F needed to move the block B is (g=10 ms−2).

If dimensions of length are expressed as Gxcyhz where G, c and h are universal gravitational constants, speed of light and Planck's constant respectively then:

Can the coefficient of friction be more than one?

Average velocity of a particle moving in a straight line, with constant acceleration ‘a’ and initial velocity 'u' in first 't' seconds is :

Figure shows a block of mass m placed on a horizontal surface. The coefficient of static friction between the block and the surface is μ. The maximum force F that can be applied at point O such that the block does not slip on the surface is

An insect of mass m crawls along the hanging thread with an acceleration a =g2. The normal reaction offered by ground on the block of mass 2m kept stationary on ground is

The vector having magnitude equal to 5 and perpendicular to the vector →B=2^i−3^j+2^k and making equal angle with the positive X-axis and the positive Y-axis is

A uniform solid sphere of radius R has a cavity of radius 1 m cut from it. If the centre of mass of the system lies at the periphery of the cavity, then:

A rod is measured using a scale. The reading is 60 cm at 12∘C. If thermal coefficient of linear expansion of the rod is 3×10−5/∘C, the reading of the rod at 42∘C is: (Assume the scale does not expand)

A power P=2t3 is applied to the particle. If the kinetic energy of the particle is K and velocity is v then

A wheel makes 360 revolutions in one minute. Through how many radians does it turn in one second?

Two small spheres each having the charge +Q are suspended by insulating threads of length L from a hook. This arrangement is taken in space where there is no gravitational effect. Then the angle between the two threads at the point of suspension and the tension in each thread will be

The elevator starts from the ground floor and goes up to the 4th floor it drops a person and comes down to the first floor then displacement in both the cases are?

The engine of a motorcycle can produce a max acc. of 5 mtr per sec square. Its brakes can produce a maximum retardation of 10 mtr per sec square. What is the min time in which it can cover a distance of 1.5km.?

In the circuit shown in the following figure E=10 V,R1=2 ohm,R2=3 ohm and R3=6 ohm and L=5 henry . The current I1 just after pressing the switch S is (correct answer + 2, wrong answer - 0.50)

At t=0 a projectile is fired from a point O (taken as origin) on the ground with a speed of 50 m/s at an angle of 53∘ with the horizontal. It just passes two points A and B each at height 75 m above horizontal as shown. The horizontal separation between the points A and B is (Take g=10 m/s2)

can moment of inertia of an body be defined about a point (that is not an axis)

An alternating emf is applied across a parallel combination of a resistance R, capacitance C and an inductance L. If IR,IL,IC are the currents through R,L and C respectively, then the diagram which correctly represents, the phase relationship among IR,IL,IC and source emf E, is given by

What would happen in the context of charging by induction if instead of bring a charged and an uncharged body close to each other we bring two charged bodies close to each other?

The kinetic energy of 1 mole of oxygen molecules in cal mol−1 at 27∘C is__.

Why Earth behave like a magnet? Explain magnetic elements of earth at a place giving expressions.

An iron nail is dropped from a height h from the level of a sand bed. If it penetrates through a distance x in the sand before coming to rest, the average force exerted by the sand on the nail is,

I'm not understanding about the topic fundamental and derived units.

When iron(rod) is in solid form then how it's molecules are in gaseous state ?

A solid sphere and a disc are released from the top of an inclined plane such that both are rolling with slipping if ts and td are their respective time of journey to the bottom of plain then prove that ts= td

I I could not understand how to derive an derivative by integration as well as differentiations so please tell me how to derive and derivative using integration and differentiation

The moment of inertia of a circular ring about an axis passing through its center and normal to its plane is 200 gm−cm2. Then its moment of inertia about a diameter is

Can superconductors exhibit resonance ? Why or why not ?

A vessel contains 1 mole of O2 gas (molar mass 32) at a temperature T. The pressure of the gas is P. An identical vessel containing one mole of He gas (molar mass 4) at a temperature 2T has a pressure of

A rod of mass ′M′ and length ′L′ lies on horizontal table and hinged at its one end. A particle of mass ′m′ is moving with velocity ′v′ and it hits perpendicularly to other end of the rod. If particles sticks to the rod after collision, then find the angular velocity of the rod.

A stone dropped from a certain height reaches ground in 5 sec. If it is dropped and stopped for infinitesimal time interval at t=3 s, then time taken by the stone to reach the ground is

z¯¯¯z = 0 if and only if:

Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k is T when block is uncharged. If a charge q is given to the block then, the new time period of oscillation will be

Two terminals of a cell of emf 2.5 V are connected to the two ends of the 10 ohm resistance coil. If the current in the circuit is 0.2 A, then the internal resistance of the cell is