50278 + Interview Questions in Physics

1.	A body of mass 10 kg moving with velocity of 10 m/s hits another body of mass 30 kg moving with velocity 3 m/s in same direction. The co-efficient of restitution is 14. The velocity of centre of mass after collision will be
Answer» A body of mass $10 kg$ moving with velocity of $10 m/s$ hits another body of mass $30 kg$ moving with velocity $3 m/s$ in same direction. The co-efficient of restitution is $\frac{1}{4}$ . The velocity of centre of mass after collision will be

Discussion

2.	The specific resistance of a wire is ρ, its volume is 3 m3 and its resistance is 3 Ω, then its length will be
Answer» The specific resistance of a wire is $ρ$ , its volume is $3 m^{3}$ and its resistance is $3 Ω$ , then its length will be

Discussion

3.	Two masses A and B of 5 kg and 6 kg are connected by a string passing over a frictionless pulley fixed at the corner of table as shown in figure. The coefficient of friction between A and the table is 0.3. The minimum mass of C that must be placed on A to prevent it from moving is equal to: (Take =10 m/s2)
Answer» Two masses $A$ and $B$ of $5 kg$ and $6 kg$ are connected by a string passing over a frictionless pulley fixed at the corner of table as shown in figure. The coefficient of friction between $A$ and the table is $0.3$ . The minimum mass of $C$ that must be placed on $A$ to prevent it from moving is equal to: $(Take = 10 {m/s}^{2})$

Discussion

4.	A rectangular conductor LMNO is placed in a uniform magnetic field of 0.5T. The field is directed perpendicular to the plane of the conductor. When the arm MN of length of 20cm is moved towards left with a velocity of 10ms−1, calculate the emf induced in the arm. Given the resistance of the arm to be 5Ω, (assuming that other arms are of negligible resistance) find the value of the current in the arm.
Answer» A rectangular conductor LMNO is placed in a uniform magnetic field of $0.5 T$ . The field is directed perpendicular to the plane of the conductor. When the arm $M N$ of length of $20 c m$ is moved towards left with a velocity of $10 m s^{- 1}$ , calculate the emf induced in the arm. Given the resistance of the arm to be $5 Ω$ , (assuming that other arms are of negligible resistance) find the value of the current in the arm.

Discussion

5.	Doubt in performing question on topic Doppler effect and moment of inertia
Answer» Doubt in performing question on topic Doppler effect and moment of inertia

Discussion

6.	A block of mass m is placed on a triangular block of mass M, which in turn is placed on a horizontal surface as shown in figure (9-E21). Assuming frictionless surfaces find the velocity of the triangular block when the smaller block reaches the bottom end.
Answer» A block of mass m is placed on a triangular block of mass M, which in turn is placed on a horizontal surface as shown in figure (9-E21). Assuming frictionless surfaces find the velocity of the triangular block when the smaller block reaches the bottom end.

6.

A block of mass m is placed on a triangular block of mass M, which in turn is placed on a horizontal surface as shown in figure (9-E21). Assuming frictionless surfaces find the velocity of the triangular block when the smaller block reaches the bottom end.

Answer»

A block of mass m is placed on a triangular block of mass M, which in turn is placed on a horizontal surface as shown in figure (9-E21). Assuming frictionless surfaces find the velocity of the triangular block when the smaller block reaches the bottom end.

Discussion

7.	In a vibration magnetometer, the time period of a bar magnet oscillating in horizontal component of earth's magnetic field is 2 sec. When a magnet is brought near and parallel to it, the time period reduces to 1 sec. The ratio H/F of the horizontal component H and the field F due to magnet will be
Answer» In a vibration magnetometer, the time period of a bar magnet oscillating in horizontal component of earth's magnetic field is 2 sec. When a magnet is brought near and parallel to it, the time period reduces to 1 sec. The ratio H/F of the horizontal component H and the field F due to magnet will be

Discussion

8.	An iceberg is floating partially immersed in seawater. The density of seawater is 1.03 g cm−3 and that of ice is 0.92 g cm−3. The approximate percentage of the total volume of the iceberg above the level of seawater is
Answer» An iceberg is floating partially immersed in seawater. The density of seawater is $1.03 g c m^{- 3}$ and that of ice is $0.92 g c m^{- 3}$ . The approximate percentage of the total volume of the iceberg above the level of seawater is

Discussion

9.	An electron moving with a speed of 5×106 ms−1 is shot parallel to an electric field of strength 1000 Vm−1, arranged so as to retard its motion. The electron travels a distance s in the field before coming momentarily to rest in time t. It is observed that the electric field ends abruptly after 0.85 cm and due to this the electron loses a percentage fraction f of its initial energy, then
Answer» An electron moving with a speed of $5 \times 10^{6} m s^{- 1}$ is shot parallel to an electric field of strength $1000 V m^{- 1}$ , arranged so as to retard its motion. The electron travels a distance s in the field before coming momentarily to rest in time t. It is observed that the electric field ends abruptly after 0.85 cm and due to this the electron loses a percentage fraction f of its initial energy, then

Discussion

10.	The angular velocity of the earth with which it has to rotate so that acceleration due to gravity on 60∘ latitude becomes zero is (Radius of earth = 6400 At the poles g = 10ms−2)
Answer» The angular velocity of the earth with which it has to rotate so that acceleration due to gravity on $60^{\circ}$ latitude becomes zero is (Radius of earth = 6400 At the poles g = 10 $m s^{- 2}$ )

Discussion

11.	In the angle subtended by vector ˆi+ˆj with the x - axis is
Answer» In the angle subtended by vector $ˆ i + ˆ j$ with the x - axis is

Discussion

12.	A metal block of density 6000 kg m−3 and mass 1.2 kg is suspended through a spring of spring constant 200 N m−1. The spring-block system is dipped in water kept in a vessel. The water has a mass of 260 g and the block is at a height 40 cm above the bottom of the vessel. If the support to the spring is broken, what will be the rise in the temperature of the water. Specific heat capacity of the block is 250 J kg−1K−1 and that of water is 4200 J kg−1K−1. The heat capacities of the vessel and the spring are negligible.
Answer» A metal block of density 6000 kg $m^{- 3}$ and mass 1.2 kg is suspended through a spring of spring constant 200 N $m^{- 1}$ . The spring-block system is dipped in water kept in a vessel. The water has a mass of 260 g and the block is at a height 40 cm above the bottom of the vessel. If the support to the spring is broken, what will be the rise in the temperature of the water. Specific heat capacity of the block is 250 J $k g^{- 1} K^{- 1}$ and that of water is 4200 J $k g^{- 1} K^{- 1}$ . The heat capacities of the vessel and the spring are negligible.

Discussion

13.	A wave is described by the equation y=(1.0 mm)sin π(x2.0 cm−t0.01 s) (a) Find the time period and the wavelength ? (b) Write the equation for the velocity of the particles. Find the speed of the particle at x = 1.0 cm at time t = 0.01 s. (c) What are the speeds of the particles at x = 3.0 cm, 5.0 cm and 7.0 cm at t = 0.01 s ? (d) What are the speeds of the particles at x = 1.0 cm at t = 0.011, 0.012, and 0.013 s?
Answer» A wave is described by the equation $y = (1.0 m m) s i n π (\frac{x}{2.0 c m} - \frac{t}{0.01 s})$ (a) Find the time period and the wavelength ? (b) Write the equation for the velocity of the particles. Find the speed of the particle at x = 1.0 cm at time t = 0.01 s. (c) What are the speeds of the particles at x = 3.0 cm, 5.0 cm and 7.0 cm at t = 0.01 s ? (d) What are the speeds of the particles at x = 1.0 cm at t = 0.011, 0.012, and 0.013 s?

Discussion

14.	A bus starts moving with acceleration 2 ms−2. A cyclist 96 m behind the bus starts simultaneously toward the bus at a constant speed of 20 m/s. After some time, the bus will be left behind. If the bus continues moving with the same acceleration, after what time from the beginning, the bus will overtake the cyclist?
Answer» A bus starts moving with acceleration $2 {ms}^{- 2}$ . A cyclist $96 m$ behind the bus starts simultaneously toward the bus at a constant speed of $20 m/s$ . After some time, the bus will be left behind. If the bus continues moving with the same acceleration, after what time from the beginning, the bus will overtake the cyclist?

Discussion

15.	A man of mass M=50 kg standing on the edge of a platform (moment of inertia of the platform is I and radius R=1 m) is rotating in anticlockwise direction at an angular speed of 20 rad/s. The man starts walking along the rim with a speed 1 m/s relative to the platform, also in the anticlockwise direction. The new angular speed of the platform in (rad/s) is (take (I=0.02 kg-m2))
Answer» A man of mass $M = 50 kg$ standing on the edge of a platform (moment of inertia of the platform is $I$ and radius $R = 1 m$ ) is rotating in anticlockwise direction at an angular speed of $20 rad/s$ . The man starts walking along the rim with a speed $1 m/s$ relative to the platform, also in the anticlockwise direction. The new angular speed of the platform in $(rad/s)$ is (take $(I = 0.02 {kg-m}^{2})$ )

Discussion

16.	A ball after freely falling from a height of 4.9 m strikes a fixed horizontal plane. If the coefficient of restitution is 34, the ball will strike second time with the plane after
Answer» A ball after freely falling from a height of $4.9 m$ strikes a fixed horizontal plane. If the coefficient of restitution is $\frac{3}{4}$ , the ball will strike second time with the plane after

Discussion

17.	An ideal refrigerator has a freezer at a temperature of −13∘C. The coefficient of performance of the engine used is 5. The temperature of the air (to which heat is rejected) will be
Answer» An ideal refrigerator has a freezer at a temperature of $- 13^{\circ} C$ . The coefficient of performance of the engine used is $5$ . The temperature of the air (to which heat is rejected) will be

Discussion

18.	A system consists of Block A and B of masses 5 kg each and connected to a pulley as shown in figure. Find the minimum value of force F at which they will start moving? (Assume g=10 m/s2).
Answer» A system consists of Block $A$ and $B$ of masses $5 kg$ each and connected to a pulley as shown in figure. Find the minimum value of force $F$ at which they will start moving? (Assume $g = 10 {m/s}^{2}$ ).

Discussion

19.	The power delivered in the plate circuit of a diode is 1.0 W when the plate voltage is 36 V. Find the power delivered if the plate voltage is increased to 49 V. Assume langmuir - Child equation to hold.
Answer» The power delivered in the plate circuit of a diode is 1.0 W when the plate voltage is 36 V. Find the power delivered if the plate voltage is increased to 49 V. Assume langmuir - Child equation to hold.

Discussion

20.	Which of the following is not an element of communication process ?
Answer» Which of the following is not an element of communication process ?

Discussion

21.	Two forces of magnitude F have a resultant of the same magnitude F. The angle between the two forces is
Answer» Two forces of magnitude F have a resultant of the same magnitude F. The angle between the two forces is

Discussion

22.	During a tennis match, a player serves at 23.6 ms−1, the ball leaving the racquet horizontally 2.37 m above the court surface. By how much does the ball clear the net which is 12 m away and 0.9 m high? (Write the answer in metres)
Answer» During a tennis match, a player serves at $23.6 {ms}^{- 1}$ , the ball leaving the racquet horizontally $2.37 m$ above the court surface. By how much does the ball clear the net which is $12 m$ away and $0.9 m$ high? (Write the answer in metres)

Discussion

23.	A point moves with uniform acceleration and v1,v2 and v3 denote the average velocities in the three successive intervals of time t1,t2 and t3 Which of the following relations is correct
Answer» A point moves with uniform acceleration and $v_{1}, v_{2} a n d v_{3}$ denote the average velocities in the three successive intervals of time $t_{1}, t_{2} a n d t_{3}$ Which of the following relations is correct

Discussion

24.	If you move 5 km north, 5 km east and 5 km south, then your displacement is.
Answer» If you move 5 km north, 5 km east and 5 km south, then your displacement is.

Discussion

25.	Activity of a radioactive element decreased to one third of original activity I0 in 9 years. After further 9 years, its activity will be
Answer» Activity of a radioactive element decreased to one third of original activity $I_{0}$ in $9 y e a r s$ . After further $9 y e a r s$ , its activity will be

Discussion

26.	Area of muzzle is A. Due to ejection of water (density = ρ) at a velocity v, the spring is compressed as shown in figure. The compression in spring, in equilibrium, is
Answer» Area of muzzle is $A$ . Due to ejection of water (density = $ρ$ ) at a velocity $v$ , the spring is compressed as shown in figure. The compression in spring, in equilibrium, is

Discussion

27.	In the figure shown, a body of mass 6 kg is at a distance of 16 m from the pulley at t=0 when it is released. If the string is cut after 2 s, then find the time after which the 6 kg block will hit the pulley. Consider the surface to be smooth (Take g=10 m/s2)
Answer» In the figure shown, a body of mass $6 k g$ is at a distance of $16 m$ from the pulley at $t = 0$ when it is released. If the string is cut after $2 s$ , then find the time after which the $6 k g$ block will hit the pulley. Consider the surface to be smooth (Take $g = 10 m / s^{2}$ )

Discussion

28.	Two point charges A and B having charges +q and –q respectively are placed at certain distance apart and force acting between them is F. If 25% charge of A is transferred to B, force between the charges becomes
Answer» Two point charges A and B having charges $+ q$ and $- q$ respectively are placed at certain distance apart and force acting between them is $F$ . If 25% charge of A is transferred to B, force between the charges becomes

Discussion

29.	The sulphate contains 9.87 % of M . this sulphate is isomorphous with ZNSO4.7H2O the atomic weight of M is :
Answer» The sulphate contains 9.87 % of M . this sulphate is isomorphous with ZNSO4.7H2O the atomic weight of M is :

Discussion

30.	The coefficient of volume expansion of a liquid is 5×10−4 ∘C−1. If its temperature is increased by 30∘C, the percentage change in its density is
Answer» The coefficient of volume expansion of a liquid is $5 \times 10^{- 4} {^{\circ} C}^{- 1}$ . If its temperature is increased by $30^{\circ} C$ , the percentage change in its density is

Discussion

31.	is lift excluded from gravity in numericals of motion in one dimension
Answer» is lift excluded from gravity in numericals of motion in one dimension

Discussion

32.	A man of mass m stands on a crate of mass M. He pulls on a light rope passing over a smooth light pulley. The other end of the rope is attached to the crate. For the system to be in equilibrium, the force exerted by the man on the rope will be
Answer» A man of mass $m$ stands on a crate of mass $M$ . He pulls on a light rope passing over a smooth light pulley. The other end of the rope is attached to the crate. For the system to be in equilibrium, the force exerted by the man on the rope will be

Discussion

33.	The cylindrical tube of a spray pump has radius of 5 cm, one end of which has 10 fine holes each of radius 0.1 cm. If the speed of liquid in the tube is 1 m/s, the speed of the ejection of the liquid through the holes is
Answer» The cylindrical tube of a spray pump has radius of $5 cm$ , one end of which has $10$ fine holes each of radius $0.1 cm$ . If the speed of liquid in the tube is $1 m/s$ , the speed of the ejection of the liquid through the holes is

Discussion

34.	The velocity of a particle at time t is given by the relation v=6t−t26. The distance traveled in 3 seconds is, if s=0 at t=0
Answer» The velocity of a particle at time t is given by the relation $v = 6 t - \frac{t^{2}}{6}$ . The distance traveled in 3 seconds is, if s=0 at t=0

Discussion

35.	A vector is represented by 3^i+^j+2^k. Its length in XY plane is
Answer» A vector is represented by $3^i +^j + 2^k$ . Its length in $X Y$ plane is

Discussion

36.	A 50 kg person stands on a 25 kg platform. He pulls the rope which is attached to the platform through the frictionless pulleys as shown in the figure. If the platform moves upwards at a steady velocity, find the force with which man pulls the rope. Take g=10 m/s2.
Answer» A $50 kg$ person stands on a $25 kg$ platform. He pulls the rope which is attached to the platform through the frictionless pulleys as shown in the figure. If the platform moves upwards at a steady velocity, find the force with which man pulls the rope. Take $g = 10 {m/s}^{2}$ .

Discussion

37.	Two trains Q and P are moving along parallel tracks with same uniform speed of 20 m/s .The driver of train Q decides to overtake train P and accelerates his train by 1 m/s2. After 50 s, train Q crosses the engine of train P. Given the length of each train is 400 m, the initial distance between the two trains was
Answer» Two trains $Q$ and $P$ are moving along parallel tracks with same uniform speed of $20 m/s$ .The driver of train $Q$ decides to overtake train $P$ and accelerates his train by $1 {m/s}^{2}$ . After $50 s$ , train $Q$ crosses the engine of train $P$ . Given the length of each train is $400 m$ , the initial distance between the two trains was

Discussion

38.	If y=[x2+2x3x−4], then dydx=?
Answer» If $y = [\frac{x^{2} + 2 x}{3 x - 4}], t h e n \frac{d y}{d x}$ =?

Discussion

39.	Two cars P and Q move with velocities →vP and →vQ towards north and east respectively. Velocity of car P w.r.t. Q (i.e., velocity of car P for an observer on cars Q) i.e., →vPQ will be in which direction?
Answer» Two cars P and Q move with velocities ${\to v}_{P}$ and ${\to v}_{Q}$ towards north and east respectively. Velocity of car P w.r.t. Q (i.e., velocity of car P for an observer on cars Q) i.e., ${\to v}_{P Q}$ will be in which direction?

39.

Two cars P and Q move with velocities →vP and →vQ towards north and east respectively. Velocity of car P w.r.t. Q (i.e., velocity of car P for an observer on cars Q) i.e., →vPQ will be in which direction?

Answer»

Two cars P and Q move with velocities ${\to v}_{P}$ and ${\to v}_{Q}$ towards north and east respectively.

Velocity of car P w.r.t. Q (i.e., velocity of car P for an observer on cars Q) i.e., ${\to v}_{P Q}$ will be in which direction?

Discussion

40.	Due to a point isotropic sound source, the sound level at a point is observed as 40 dB. The density of air is ρ = 1511kg/m3 and velocity of sound in air is 330 m/s. (The threshold intensity is 10−12Wm2) The pressure amplitude at the observation point is x(10−3)N/m2. Then x = _____
Answer» Due to a point isotropic sound source, the sound level at a point is observed as $40 d B$ . The density of air is $ρ$ = $\frac{15}{11} k g / m^{3}$ and velocity of sound in air is $330 m / s$ . (The threshold intensity is $10^{- 12} \frac{W}{m^{2}}$ ) The pressure amplitude at the observation point is $x (10^{- 3}) N / m^{2}$ . Then $x$ = _____

40.

Due to a point isotropic sound source, the sound level at a point is observed as 40 dB. The density of air is ρ = 1511kg/m3 and velocity of sound in air is 330 m/s. (The threshold intensity is 10−12Wm2) The pressure amplitude at the observation point is x(10−3)N/m2. Then x = _____

Answer»

Due to a point isotropic sound source, the sound level at a point is observed as $40 d B$ . The density of air is $ρ$ = $\frac{15}{11} k g / m^{3}$ and velocity of sound in air is $330 m / s$ . (The threshold intensity is $10^{- 12} \frac{W}{m^{2}}$ )

The pressure amplitude at the observation point is $x (10^{- 3}) N / m^{2}$ . Then $x$ = _____

Discussion

41.	Convert (-3)radiant into corresponding degree minutes and seconds
Answer» Convert (-3)radiant into corresponding degree minutes and seconds

Discussion

42.	Two metallic spheres A and B of same radii one silso and one hollow are charged with the same potential. Which of the two will have more charge A) sphere A B) sphere B C)both D) none of the two
Answer» Two metallic spheres A and B of same radii one silso and one hollow are charged with the same potential. Which of the two will have more charge A) sphere A B) sphere B C)both D) none of the two

42.

Two metallic spheres A and B of same radii one silso and one hollow are charged with the same potential. Which of the two will have more charge A) sphere A B) sphere B C)both D) none of the two

Answer»

Two metallic spheres A and B of same radii one silso and one hollow are charged with the same potential. Which of the two will have more charge

A) sphere A

B) sphere B

C)both

D) none of the two

Discussion

43.	What is Raman spectroscopy? Is a type of line or continuous spectrum?
Answer» What is Raman spectroscopy? Is a type of line or continuous spectrum?

Discussion

44.	A highly rigid cubical block A of small mass M and side L is fixed rigidly on to another cubical block B of the same dimensions and of low modulus of rigidity h such that the lower face of A completely covers the upper face of B. The lower face of B is rigidly held on a horizontal surface. A small force F is applied perpendicular to one of the side faces of A. After the force is withdrawn, block A executes small oscillations, the time period of which is given by :
Answer» A highly rigid cubical block A of small mass M and side L is fixed rigidly on to another cubical block B of the same dimensions and of low modulus of rigidity h such that the lower face of A completely covers the upper face of B. The lower face of B is rigidly held on a horizontal surface. A small force F is applied perpendicular to one of the side faces of A. After the force is withdrawn, block A executes small oscillations, the time period of which is given by :

Discussion

45.	Why is it easier to balance a bicycle in motion?
Answer» Why is it easier to balance a bicycle in motion?

Discussion

46.	Can potential energy be negative? Explain
Answer» Can potential energy be negative? Explain

Discussion

47.	Refrigerators X and Y are removing 1000 J of heat from the freezer. Refrigerator X is working between -5o C and 25o C and refrigerator Y is working between -20o C and 20oC. Find efficiency of refrigerator X and Y?
Answer» Refrigerators X and Y are removing 1000 J of heat from the freezer. Refrigerator X is working between -5^o C and 25^o C and refrigerator Y is working between -20^o C and 20^oC. Find efficiency of refrigerator X and Y?

Discussion

48.	A parachutist drops first freely from an airplane for 10 s and then the parachute opens out. Now he descends with net retardation of 2.5 m/s2. If he bails out of the plane at a height of 2495 m and g=10 m/s2, his velocity on reaching the ground will be
Answer» A parachutist drops first freely from an airplane for $10 s$ and then the parachute opens out. Now he descends with net retardation of $2.5 m / s^{2}$ . If he bails out of the plane at a height of $2495 m$ and $g = 10 m / s^{2}$ , his velocity on reaching the ground will be

Discussion

49.	In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wing are 70ms–1 and 63ms–1 respectively. What is the lift on the wing if its area is 2.5 m2? Take the density of air to be 1.3 kg m–3.
Answer» In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wing are $70 m s^{- 1}$ and $63 m s^{- 1}$ respectively. What is the lift on the wing if its area is 2.5 $m^{2}$ ? Take the density of air to be 1.3 kg $m^{- 3}$ .

Discussion

50.	A ray of light is incident at an angle i from denser to rare medium. The reflected and the refracted rays are mutually perpendicular. The angle of reflection and the angle of refraction are respectively r and r’, then the critical angle will be
Answer» A ray of light is incident at an angle i from denser to rare medium. The reflected and the refracted rays are mutually perpendicular. The angle of reflection and the angle of refraction are respectively r and r’, then the critical angle will be

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A body of mass 10 kg moving with velocity of 10 m/s hits another body of mass 30 kg moving with velocity 3 m/s in same direction. The co-efficient of restitution is 14. The velocity of centre of mass after collision will be

The specific resistance of a wire is ρ, its volume is 3 m3 and its resistance is 3 Ω, then its length will be

Doubt in performing question on topic Doppler effect and moment of inertia

A block of mass m is placed on a triangular block of mass M, which in turn is placed on a horizontal surface as shown in figure (9-E21). Assuming frictionless surfaces find the velocity of the triangular block when the smaller block reaches the bottom end.

In a vibration magnetometer, the time period of a bar magnet oscillating in horizontal component of earth's magnetic field is 2 sec. When a magnet is brought near and parallel to it, the time period reduces to 1 sec. The ratio H/F of the horizontal component H and the field F due to magnet will be

An iceberg is floating partially immersed in seawater. The density of seawater is 1.03 g cm−3 and that of ice is 0.92 g cm−3. The approximate percentage of the total volume of the iceberg above the level of seawater is

The angular velocity of the earth with which it has to rotate so that acceleration due to gravity on 60∘ latitude becomes zero is (Radius of earth = 6400 At the poles g = 10ms−2)

In the angle subtended by vector ˆi+ˆj with the x - axis is

A ball after freely falling from a height of 4.9 m strikes a fixed horizontal plane. If the coefficient of restitution is 34, the ball will strike second time with the plane after

An ideal refrigerator has a freezer at a temperature of −13∘C. The coefficient of performance of the engine used is 5. The temperature of the air (to which heat is rejected) will be

A system consists of Block A and B of masses 5 kg each and connected to a pulley as shown in figure. Find the minimum value of force F at which they will start moving? (Assume g=10 m/s2).

The power delivered in the plate circuit of a diode is 1.0 W when the plate voltage is 36 V. Find the power delivered if the plate voltage is increased to 49 V. Assume langmuir - Child equation to hold.

Which of the following is not an element of communication process ?

Two forces of magnitude F have a resultant of the same magnitude F. The angle between the two forces is

During a tennis match, a player serves at 23.6 ms−1, the ball leaving the racquet horizontally 2.37 m above the court surface. By how much does the ball clear the net which is 12 m away and 0.9 m high? (Write the answer in metres)

A point moves with uniform acceleration and v1,v2 and v3 denote the average velocities in the three successive intervals of time t1,t2 and t3 Which of the following relations is correct

If you move 5 km north, 5 km east and 5 km south, then your displacement is.

Activity of a radioactive element decreased to one third of original activity I0 in 9 years. After further 9 years, its activity will be

Area of muzzle is A. Due to ejection of water (density = ρ) at a velocity v, the spring is compressed as shown in figure. The compression in spring, in equilibrium, is

In the figure shown, a body of mass 6 kg is at a distance of 16 m from the pulley at t=0 when it is released. If the string is cut after 2 s, then find the time after which the 6 kg block will hit the pulley. Consider the surface to be smooth (Take g=10 m/s2)

Two point charges A and B having charges +q and –q respectively are placed at certain distance apart and force acting between them is F. If 25% charge of A is transferred to B, force between the charges becomes

The sulphate contains 9.87 % of M . this sulphate is isomorphous with ZNSO4.7H2O the atomic weight of M is :

The coefficient of volume expansion of a liquid is 5×10−4 ∘C−1. If its temperature is increased by 30∘C, the percentage change in its density is

is lift excluded from gravity in numericals of motion in one dimension

A man of mass m stands on a crate of mass M. He pulls on a light rope passing over a smooth light pulley. The other end of the rope is attached to the crate. For the system to be in equilibrium, the force exerted by the man on the rope will be

The cylindrical tube of a spray pump has radius of 5 cm, one end of which has 10 fine holes each of radius 0.1 cm. If the speed of liquid in the tube is 1 m/s, the speed of the ejection of the liquid through the holes is

The velocity of a particle at time t is given by the relation v=6t−t26. The distance traveled in 3 seconds is, if s=0 at t=0

A vector is represented by 3^i+^j+2^k. Its length in XY plane is

A 50 kg person stands on a 25 kg platform. He pulls the rope which is attached to the platform through the frictionless pulleys as shown in the figure. If the platform moves upwards at a steady velocity, find the force with which man pulls the rope. Take g=10 m/s2.

If y=[x2+2x3x−4], then dydx=?

Two cars P and Q move with velocities →vP and →vQ towards north and east respectively. Velocity of car P w.r.t. Q (i.e., velocity of car P for an observer on cars Q) i.e., →vPQ will be in which direction?

Due to a point isotropic sound source, the sound level at a point is observed as 40 dB. The density of air is ρ = 1511kg/m3 and velocity of sound in air is 330 m/s. (The threshold intensity is 10−12Wm2) The pressure amplitude at the observation point is x(10−3)N/m2. Then x = _____

Convert (-3)radiant into corresponding degree minutes and seconds

Two metallic spheres A and B of same radii one silso and one hollow are charged with the same potential. Which of the two will have more charge A) sphere A B) sphere B C)both D) none of the two

What is Raman spectroscopy? Is a type of line or continuous spectrum?

Why is it easier to balance a bicycle in motion?

Can potential energy be negative? Explain

Refrigerators X and Y are removing 1000 J of heat from the freezer. Refrigerator X is working between -5o C and 25o C and refrigerator Y is working between -20o C and 20oC. Find efficiency of refrigerator X and Y?

A parachutist drops first freely from an airplane for 10 s and then the parachute opens out. Now he descends with net retardation of 2.5 m/s2. If he bails out of the plane at a height of 2495 m and g=10 m/s2, his velocity on reaching the ground will be

In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wing are 70ms–1 and 63ms–1 respectively. What is the lift on the wing if its area is 2.5 m2? Take the density of air to be 1.3 kg m–3.

A ray of light is incident at an angle i from denser to rare medium. The reflected and the refracted rays are mutually perpendicular. The angle of reflection and the angle of refraction are respectively r and r’, then the critical angle will be