50278 + Interview Questions in Physics

1.	A Pitot static tube is used to measure the airflow rate in a square tube. If Pd is the differential pressure, the flow rate is proportional to
Answer» A Pitot static tube is used to measure the airflow rate in a square tube. If $P_{d}$ is the differential pressure, the flow rate is proportional to

Discussion

2.

A stone of mass m tied to the end of a string revolves in a vertical circle of radius R. The net forces at the lowest and highest points of the circle directed vertically downwards are: [Choose the correct alternative] Lowest Point Highest Point (a) mg – T1 mg + T2 (b) mg + T1 mg – T2 (c) mg + T1 –/R mg – T2 + /R (d) mg – T1 – /R mg + T2 + /R T1 and v1 denote the tension and speed at the lowest point. T2 and v2 denote corresponding values at the highest point.

Answer»

A stone of mass m tied to the end of a string revolves in a vertical circle of radius R. The net forces at the lowest and highest points of the circle directed vertically downwards are: [Choose the correct alternative]

	Lowest Point	Highest Point
(a)	mg – T₁	mg + T₂
(b)	mg + T₁	mg – T₂
(c)	mg + T₁ –/R	mg – T₂ + /R
(d)	mg – T₁ – /R	mg + T₂ + /R

T₁and v₁ denote the tension and speed at the lowest point. T₂and v₂ denote corresponding values at the highest point.

Discussion

3.	If the number of electric lines of force emerging out of a closed surface is 1000 then the charge enclosed by the surface is
Answer» If the number of electric lines of force emerging out of a closed surface is 1000 then the charge enclosed by the surface is

Discussion

4.	A rod of length 1.05 m having negligible mass is supported at its ends by two wires of steel (wire A) and aluminium (wire B) of equal lengths as shown in Fig. 9.15. The cross-sectional areas of wires A and B are 1.0 mm² and 2.0 mm², respectively. At what point along the rod should a mass m be suspended in order to produce (a) equal stresses and (b) equal strains in both steel and aluminium wires.
Answer» A rod of length 1.05 m having negligible mass is supported at its ends by two wires of steel (wire A) and aluminium (wire B) of equal lengths as shown in Fig. 9.15. The cross-sectional areas of wires A and B are 1.0 mm² and 2.0 mm², respectively. At what point along the rod should a mass m be suspended in order to produce (a) equal stresses and (b) equal strains in both steel and aluminium wires.

Discussion

5.	Ultraviolet light of wavelength 2271 Å from a 100 W mercury sourceirradiates a photo-cell made of molybdenum metal. If the stoppingpotential is –1.3 V, estimate the work function of the metal. Howwould the photo-cell respond to a high intensity (∼105 W m–2) redlight of wavelength 6328 Å produced by a He-Ne laser ?
Answer» Ultraviolet light of wavelength 2271 Å from a 100 W mercury sourceirradiates a photo-cell made of molybdenum metal. If the stoppingpotential is –1.3 V, estimate the work function of the metal. Howwould the photo-cell respond to a high intensity (∼105 W m–2) redlight of wavelength 6328 Å produced by a He-Ne laser ?

Discussion

6.	Let t = \|ax1+by1+c√a2+b2\|. Find the length of perpendicular from p(x1,y1) on ax+by+c=0 in terms of t.
Answer» Let t = $\| \frac{a x_{1} + b y_{1} + c}{\sqrt{a^{2} + b^{2}}} \|$ . Find the length of perpendicular from $p (x_{1}, y_{1})$ on ax+by+c=0 in terms of t.

Discussion

7.	For a uniform motion what should be constant- Velocity or Speed?Are these formulas only used for uniform motion- Distance= Speed * Time Displacement= Velocity* Time
Answer» For a uniform motion what should be constant- Velocity or Speed? Are these formulas only used for uniform motion- Distance= Speed * Time Displacement= Velocity* Time

Discussion

8.	What is the graph of free fall
Answer» What is the graph of free fall

Discussion

9.	A wire carrying current is placed inside a uniform magnetic field →B=−B0^K. The shape of the wire is parabolic and has equation y=2x−x2. The force on the wire will be
Answer» A wire carrying current is placed inside a uniform magnetic field $\to B = - B_{0}^K$ . The shape of the wire is parabolic and has equation $y = 2 x - x^{2}$ . The force on the wire will be

Discussion

10.	∫x ex(1+x)2dx is equal to(where c is constant of integration)
Answer» $\int \frac{x e^{x}}{{(1 + x)}^{2}} d x$ is equal to (where $c$ is constant of integration)

Discussion

11.	In v−t graph shown in fig. the displacement of the body in 4 seconds will be, if it starts from origin.
Answer» In $v - t$ graph shown in fig. the displacement of the body in $4$ seconds will be, if it starts from origin.

Discussion

12.	Find thederivative offorsome fixed real number a.
Answer» Find the derivative offor some fixed real number a.

Discussion

13.	Fig. 14.23 depicts four x-t plots for linear motion of a particle. Which of the plots represent periodic motion? What is the period of motion (in case of periodic motion) ?
Answer» Fig. 14.23 depicts four x-t plots for linear motion of a particle. Which of the plots represent periodic motion? What is the period of motion (in case of periodic motion) ?

Discussion

14.	A light beam is being reflected by using two mirrors, as in a periscope used in submarines. If one of the mirrors rotates by an angle θ, the reflected light will deviate from its original path by the angle:-
Answer» A light beam is being reflected by using two mirrors, as in a periscope used in submarines. If one of the mirrors rotates by an angle $θ,$ the reflected light will deviate from its original path by the angle:-

Discussion

15.	A chain in the shape of circular loop of mass m and radius R is placed on a frictionless surface. Loop is given an angular velocity of ω as shown in the figure. Tension in the chain is
Answer» A chain in the shape of circular loop of mass $m$ and radius $R$ is placed on a frictionless surface. Loop is given an angular velocity of $ω$ as shown in the figure. Tension in the chain is

Discussion

16.	Why does magnetic field frame dependent only for moving charge particle ?
Answer» Why does magnetic field frame dependent only for moving charge particle ?

Discussion

17.	Five equal resistances each of resistance R are connected as shown in the figure. A battery of 4 volts is connected between A and B. The current flowing in AFCEB will be
Answer» Five equal resistances each of resistance R are connected as shown in the figure. A battery of 4 volts is connected between A and B. The current flowing in AFCEB will be

Discussion

18.	Mohit travels 10 m over a circular path having radius 10 m. Angle substended by Mohit at the center of circle is
Answer» Mohit travels $10 m$ over a circular path having radius $10 m$ . Angle substended by Mohit at the center of circle is

Discussion

19.	An electron moves a dis†an ce of 6.0 cm when aacelerated from rest by an electric field of strength 2/10000 N/C. calculate the time of travel
Answer» An electron moves a dis†an ce of 6.0 cm when aacelerated from rest by an electric field of strength 2/10000 N/C. calculate the time of travel

Discussion

20.	1cm of main scale of vernier calliper is divided into ten equal parts.if 10 divisions of the main scale coincide withb8 small division of the main scale then least count of the calliper i
Answer» 1cm of main scale of vernier calliper is divided into ten equal parts.if 10 divisions of the main scale coincide withb8 small division of the main scale then least count of the calliper i

Discussion

21.	A telescope has an objective lens of focal length 200 cm and eye piece with focal length 2 cm. If this telescope is used to see a 50 m tall building at a distance of 2 km. What is the height of the image of the building formed by the objective lens is
Answer» A telescope has an objective lens of focal length $200 cm$ and eye piece with focal length $2 cm$ . If this telescope is used to see a $50 m$ tall building at a distance of $2 km .$ What is the height of the image of the building formed by the objective lens is

Discussion

22.	A bob of mass m accelerates uniformly from rest to v1 in time t1.As a function of t, the instantaneous power delivered to the body is
Answer» A bob of mass m accelerates uniformly from rest to v₁ in time t₁.As a function of t, the instantaneous power delivered to the body is

Discussion

23.	A two dimensional object lies in x−z plane having moment of inertia IX=MR2 and IY=4MR2. Then, the moment of inertia of object along z−axis is
Answer» A two dimensional object lies in $x - z$ plane having moment of inertia $I_{X} = M R^{2}$ and $I_{Y} = 4 M R^{2}$ . Then, the moment of inertia of object along $z -$ axis is

Discussion

24.	In Quincke's experiment the sound detected is changed from a maximum to a minimum when the sliding tube is moved through a distance of 2.50 cm. Find the frequency of sound if the speed of sound in air is 340m8−1.
Answer» In Quincke's experiment the sound detected is changed from a maximum to a minimum when the sliding tube is moved through a distance of 2.50 cm. Find the frequency of sound if the speed of sound in air is $340 m 8^{- 1} .$

Discussion

25.	An air bubble is seen iside a solid sphere of glass (n=1.5) of 4 cm diametre at a distance of 1 cm from the surface of the sphere (on seeing along the diametre ) . Determine the real position of the bubble inside the sphere ??
Answer» An air bubble is seen iside a solid sphere of glass (n=1.5) of 4 cm diametre at a distance of 1 cm from the surface of the sphere (on seeing along the diametre ) . Determine the real position of the bubble inside the sphere ??

Discussion

26.	Two long straight parallel wires carries currents of 200 mA and 1 A in opposite directions. If the wires are 20 cm apart, the distance of the neutral point from the 1 A wire is- (in cm)
Answer» Two long straight parallel wires carries currents of $200 mA$ and $1 A$ in opposite directions. If the wires are $20 cm$ apart, the distance of the neutral point from the $1 A$ wire is- (in $cm$ )

Discussion

27.	Two parallel current carying conductors carrying the same current I in the same direction are seperated by a distance r. Force experienced per unit length by a conductor would be
Answer» Two parallel current carying conductors carrying the same current I in the same direction are seperated by a distance r. Force experienced per unit length by a conductor would be

Discussion

28.	A disc having charge Q , radius R is rotating with a constant angular velocity Omega about its own axis . find magnetic field at a distance x from the centre on its axis
Answer» A disc having charge Q , radius R is rotating with a constant angular velocity Omega about its own axis . find magnetic field at a distance x from the centre on its axis

Discussion

29.	The graph of displacement v/s time is shown in Fig Its corresponding velocity-time graph will be
Answer» The graph of displacement v/s time is shown in Fig Its corresponding velocity-time graph will be

Discussion

30.	A charged parallel plate capacitor has an energy U in the system. A slab of dielectric constant K is inserted, which completely fills the space between the plates. The new energy of the system will be
Answer» A charged parallel plate capacitor has an energy $U$ in the system. A slab of dielectric constant $K$ is inserted, which completely fills the space between the plates. The new energy of the system will be

Discussion

31.	stration15.A solid sphere of uniform density and radius R exerts a gravitational force of attraction F, on a partiP, distant 2R from the centre of the sphere. A spherical cavity of radius R/2 is now formed in the sphereas shown in figure. The sphere with cavity now applies a gravitational force F2 on the same particle Pthe ratio F/F
Answer» stration15.A solid sphere of uniform density and radius R exerts a gravitational force of attraction F, on a partiP, distant 2R from the centre of the sphere. A spherical cavity of radius R/2 is now formed in the sphereas shown in figure. The sphere with cavity now applies a gravitational force F2 on the same particle Pthe ratio F/F

Discussion

32.	A charge 3 μC is released from rest from a point P in an electric field where electric potential is 20 V. When the charge reaches slowly at infinity its kinetic energy becomes:
Answer» A charge $3 μ C$ is released from rest from a point $P$ in an electric field where electric potential is $20 V$ . When the charge reaches slowly at infinity its kinetic energy becomes:

Discussion

33.	The fixed part of the lever is known as:
Answer» The fixed part of the lever is known as:

Discussion

34.	A series L-C-R circuit with R = 20 Ω L = 1.5 H and C = 35μ F is connected to a variable frequency 200 V ac supply. When the frequency of the supply equals the natural frequency of the circuit, the average power transferred to the circuit in one complete cycle is
Answer» A series L-C-R circuit with R = 20 $Ω$ L = 1.5 H and C = 35 $μ$ F is connected to a variable frequency 200 V ac supply. When the frequency of the supply equals the natural frequency of the circuit, the average power transferred to the circuit in one complete cycle is

Discussion

35.	Two identical, flat, circular coils of wire each have 100 turns and a radius of 0.4 m. The coils are arranged coaxially, one beside the other, with their planes parallel and with separation 0.6 m. Each coil carries a current of 10 A as shown. Determine the magnitude of the magnetic field at a point on the common axis of the coils and midway between them.
Answer» Two identical, flat, circular coils of wire each have $100$ turns and a radius of $0.4 m$ . The coils are arranged coaxially, one beside the other, with their planes parallel and with separation $0.6 m$ . Each coil carries a current of $10 A$ as shown. Determine the magnitude of the magnetic field at a point on the common axis of the coils and midway between them.

Discussion

36.	the electric flux inside e cone oh hight h and radius
Answer» the electric flux inside e cone oh hight h and radius

Discussion

37.	The object of mass 5kg is acted upon by a force of 100 N and it is given that limiting friction is 75N and kinetic friction is 50 N . Find the acceleration of the object.
Answer» The object of mass 5kg is acted upon by a force of 100 N and it is given that limiting friction is 75N and kinetic friction is 50 N . Find the acceleration of the object.

Discussion

38.	If the degree of freedom of a gas are f, then the ratio of two specific heats CpCv is given by
Answer» If the degree of freedom of a gas are f, then the ratio of two specific heats $\frac{C_{p}}{C_{v}}$ is given by

38.

If the degree of freedom of a gas are f, then the ratio of two specific heats CpCv is given by

Answer»

If the degree of freedom of a gas are f, then the ratio of two specific heats $\frac{C_{p}}{C_{v}}$ is given by

Discussion

39.	A block slides down an inclined plane of inclination 30∘ with a constant acceleration g/4 .Coefficient of kinetic friction is given by 1N√3. Then, the value of N is
Answer» A block slides down an inclined plane of inclination $30^{\circ}$ with a constant acceleration $g / 4$ .Coefficient of kinetic friction is given by $\frac{1}{N \sqrt{3}}$ . Then, the value of $N$ is

Discussion

40.	To observed diffraction, The size of the obstacle
Answer» To observed diffraction, The size of the obstacle

Discussion

41.	A circular ring of radius r made of non conducting material is placed with it's axis parallel to a uniform electric field. The ring is rotated about a diameter through 180 degrees. Does the flux of electric field change? If yes, does it increase or decrease?
Answer» A circular ring of radius r made of non conducting material is placed with it's axis parallel to a uniform electric field. The ring is rotated about a diameter through 180 degrees. Does the flux of electric field change? If yes, does it increase or decrease?

Discussion

42.	If a particle of mass m is moving in a horizontal circle of radius r with a centripetal force (−kr2), the total energy is
Answer» If a particle of mass m is moving in a horizontal circle of radius r with a centripetal force $(- \frac{k}{r^{2}})$ , the total energy is

Discussion

43.	23.what is the moment of inertia of a sphere about an axis which is passing through its centre of mass.
Answer» 23.what is the moment of inertia of a sphere about an axis which is passing through its centre of mass.

Discussion

44.	In an arrangement shown below, the pulley is light and the string is light and inextensible, the contact force between ground and the block is F. If the system is in equilibtium and (g=10 m/s2), the value of F (in Newtons) will be (Given F is resultant of N and R)
Answer» In an arrangement shown below, the pulley is light and the string is light and inextensible, the contact force between ground and the block is $F$ . If the system is in equilibtium and $(g = 10 {m/s}^{2})$ , the value of $F$ (in Newtons) will be (Given $F$ is resultant of $N$ and $R$ )

Discussion

45.	A wooden plank of mass 20 kg is resting on a smooth horizontal floor. A man of mass 60 kg starts moving from one end of the plank to the other end. The length of the plank is 10 m. Find the displacement of the plank over the floor, when the man reaches the other end of the plank.
Answer» A wooden plank of mass $20 kg$ is resting on a smooth horizontal floor. A man of mass $60 kg$ starts moving from one end of the plank to the other end. The length of the plank is $10 m$ . Find the displacement of the plank over the floor, when the man reaches the other end of the plank.

Discussion

46.	a car is moving at 80kminverse1 is subjected to a uniform retardation and brought to rest in 70s. find (i)retardation(ii)distance travelled by the car before it comes to rest.
Answer» a car is moving at 80kminverse1 is subjected to a uniform retardation and brought to rest in 70s. find (i)retardation(ii)distance travelled by the car before it comes to rest.

Discussion

47.	19. If the displacement of an object during its motion is 100m in a time interval of 20s then calculate the avg velocity of objects with which it was moving through out his journey
Answer» 19. If the displacement of an object during its motion is 100m in a time interval of 20s then calculate the avg velocity of objects with which it was moving through out his journey

Discussion

48.	(17. A 4 kg block A is placed on the top of 8 kg block B37which rests on a smooth table.AFB QA just slips on B when a force of 12 N is applied on AThen the maximum horizontal force F applied on Bmake both A and B move together, is(a) 12 N(c) 36 N(b) 24 N(d) 48 NL
Answer» (17. A 4 kg block A is placed on the top of 8 kg block B37which rests on a smooth table.AFB QA just slips on B when a force of 12 N is applied on AThen the maximum horizontal force F applied on Bmake both A and B move together, is(a) 12 N(c) 36 N(b) 24 N(d) 48 NL

Discussion

49.	A uniform rope of length L and mass m1 hangs vertically from a rigid support. A block of mass m2 is attached to the free end of the rope. A transverse pulse of wavelength λ1 is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is λ2. The ratio λ2λ1 is
Answer» A uniform rope of length $L$ and mass $m_{1}$ hangs vertically from a rigid support. A block of mass $m_{2}$ is attached to the free end of the rope. A transverse pulse of wavelength $λ_{1}$ is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is $λ_{2}$ . The ratio $\frac{λ_{2}}{λ_{1}}$ is

Discussion

50.	A small ball 'A' of mass 'm' is attached rigidly to the end of a light rod of length 'd'. The structure rotates about an axis perpendicular to the rod and passing through its other end with an angular velocity 'ω'. Calculate the angular momentum of the system about this axis?
Answer» A small ball 'A' of mass 'm' is attached rigidly to the end of a light rod of length 'd'. The structure rotates about an axis perpendicular to the rod and passing through its other end with an angular velocity ' $ω$ '. Calculate the angular momentum of the system about this axis?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A Pitot static tube is used to measure the airflow rate in a square tube. If Pd is the differential pressure, the flow rate is proportional to

If the number of electric lines of force emerging out of a closed surface is 1000 then the charge enclosed by the surface is

Let t = |ax1+by1+c√a2+b2|. Find the length of perpendicular from p(x1,y1) on ax+by+c=0 in terms of t.

For a uniform motion what should be constant- Velocity or Speed?Are these formulas only used for uniform motion- Distance= Speed * Time Displacement= Velocity* Time

What is the graph of free fall

A wire carrying current is placed inside a uniform magnetic field →B=−B0^K. The shape of the wire is parabolic and has equation y=2x−x2. The force on the wire will be

∫x ex(1+x)2dx is equal to(where c is constant of integration)

In v−t graph shown in fig. the displacement of the body in 4 seconds will be, if it starts from origin.

Find thederivative offorsome fixed real number a.

Fig. 14.23 depicts four x-t plots for linear motion of a particle. Which of the plots represent periodic motion? What is the period of motion (in case of periodic motion) ?

A light beam is being reflected by using two mirrors, as in a periscope used in submarines. If one of the mirrors rotates by an angle θ, the reflected light will deviate from its original path by the angle:-

A chain in the shape of circular loop of mass m and radius R is placed on a frictionless surface. Loop is given an angular velocity of ω as shown in the figure. Tension in the chain is

Why does magnetic field frame dependent only for moving charge particle ?

Five equal resistances each of resistance R are connected as shown in the figure. A battery of 4 volts is connected between A and B. The current flowing in AFCEB will be

Mohit travels 10 m over a circular path having radius 10 m. Angle substended by Mohit at the center of circle is

An electron moves a dis†an ce of 6.0 cm when aacelerated from rest by an electric field of strength 2/10000 N/C. calculate the time of travel

1cm of main scale of vernier calliper is divided into ten equal parts.if 10 divisions of the main scale coincide withb8 small division of the main scale then least count of the calliper i

A telescope has an objective lens of focal length 200 cm and eye piece with focal length 2 cm. If this telescope is used to see a 50 m tall building at a distance of 2 km. What is the height of the image of the building formed by the objective lens is

A bob of mass m accelerates uniformly from rest to v1 in time t1.As a function of t, the instantaneous power delivered to the body is

A two dimensional object lies in x−z plane having moment of inertia IX=MR2 and IY=4MR2. Then, the moment of inertia of object along z−axis is

In Quincke's experiment the sound detected is changed from a maximum to a minimum when the sliding tube is moved through a distance of 2.50 cm. Find the frequency of sound if the speed of sound in air is 340m8−1.

An air bubble is seen iside a solid sphere of glass (n=1.5) of 4 cm diametre at a distance of 1 cm from the surface of the sphere (on seeing along the diametre ) . Determine the real position of the bubble inside the sphere ??

Two long straight parallel wires carries currents of 200 mA and 1 A in opposite directions. If the wires are 20 cm apart, the distance of the neutral point from the 1 A wire is- (in cm)

Two parallel current carying conductors carrying the same current I in the same direction are seperated by a distance r. Force experienced per unit length by a conductor would be

A disc having charge Q , radius R is rotating with a constant angular velocity Omega about its own axis . find magnetic field at a distance x from the centre on its axis

The graph of displacement v/s time is shown in Fig Its corresponding velocity-time graph will be

A charged parallel plate capacitor has an energy U in the system. A slab of dielectric constant K is inserted, which completely fills the space between the plates. The new energy of the system will be

A charge 3 μC is released from rest from a point P in an electric field where electric potential is 20 V. When the charge reaches slowly at infinity its kinetic energy becomes:

The fixed part of the lever is known as:

A series L-C-R circuit with R = 20 Ω L = 1.5 H and C = 35μ F is connected to a variable frequency 200 V ac supply. When the frequency of the supply equals the natural frequency of the circuit, the average power transferred to the circuit in one complete cycle is

the electric flux inside e cone oh hight h and radius

The object of mass 5kg is acted upon by a force of 100 N and it is given that limiting friction is 75N and kinetic friction is 50 N . Find the acceleration of the object.

If the degree of freedom of a gas are f, then the ratio of two specific heats CpCv is given by

A block slides down an inclined plane of inclination 30∘ with a constant acceleration g/4 .Coefficient of kinetic friction is given by 1N√3. Then, the value of N is

To observed diffraction, The size of the obstacle

A circular ring of radius r made of non conducting material is placed with it's axis parallel to a uniform electric field. The ring is rotated about a diameter through 180 degrees. Does the flux of electric field change? If yes, does it increase or decrease?

If a particle of mass m is moving in a horizontal circle of radius r with a centripetal force (−kr2), the total energy is

23.what is the moment of inertia of a sphere about an axis which is passing through its centre of mass.

In an arrangement shown below, the pulley is light and the string is light and inextensible, the contact force between ground and the block is F. If the system is in equilibtium and (g=10 m/s2), the value of F (in Newtons) will be (Given F is resultant of N and R)

A wooden plank of mass 20 kg is resting on a smooth horizontal floor. A man of mass 60 kg starts moving from one end of the plank to the other end. The length of the plank is 10 m. Find the displacement of the plank over the floor, when the man reaches the other end of the plank.

a car is moving at 80kminverse1 is subjected to a uniform retardation and brought to rest in 70s. find (i)retardation(ii)distance travelled by the car before it comes to rest.

19. If the displacement of an object during its motion is 100m in a time interval of 20s then calculate the avg velocity of objects with which it was moving through out his journey

(17. A 4 kg block A is placed on the top of 8 kg block B37which rests on a smooth table.AFB QA just slips on B when a force of 12 N is applied on AThen the maximum horizontal force F applied on Bmake both A and B move together, is(a) 12 N(c) 36 N(b) 24 N(d) 48 NL

A small ball 'A' of mass 'm' is attached rigidly to the end of a light rod of length 'd'. The structure rotates about an axis perpendicular to the rod and passing through its other end with an angular velocity 'ω'. Calculate the angular momentum of the system about this axis?