50278 + Interview Questions in Physics

1.	A uniform circular disc of mass 1 kg and radius 0.5 m is rotating about its axis with a constant angular velocity 5 rad/sec. Two birds, each of mass 0.25 kg sit gently at the opposite ends of the diameter of the disc. The final angular velocity of the disc will be
Answer» A uniform circular disc of mass $1 kg$ and radius $0.5 m$ is rotating about its axis with a constant angular velocity $5 rad/sec$ . Two birds, each of mass $0.25 kg$ sit gently at the opposite ends of the diameter of the disc. The final angular velocity of the disc will be

Discussion

2.	(a) Find the moment of inertia of a sphere about a tangent to the sphere, given the moment of inertia of the sphere about any of its diameters to be 2MR2/5, where M is the mass of the sphere and R is the radius of the sphere. (b) Given the moment of inertia of a disc of mass M and radius R about any of its diameters to be MR2/4, find its moment of inertia about an axis normal to the disc and passing through a point on its edge.
Answer» (a) Find the moment of inertia of a sphere about a tangent to the sphere, given the moment of inertia of the sphere about any of its diameters to be $2 M R^{2} / 5$ , where M is the mass of the sphere and R is the radius of the sphere. (b) Given the moment of inertia of a disc of mass M and radius R about any of its diameters to be $M R^{2} / 4$ , find its moment of inertia about an axis normal to the disc and passing through a point on its edge.

Discussion

3.	The wave number of the energy emitted when electron comes from fourth orbit to second orbit in hydrogen is 20,397 cm−1. The wave number of the energy for the same transition in He+ is
Answer» The wave number of the energy emitted when electron comes from fourth orbit to second orbit in hydrogen is $20, 397 c m^{- 1}$ . The wave number of the energy for the same transition in $H e^{+}$ is

Discussion

4.	What is the magnitude of coulomb force between two charges placed in a medium of electrical permittivity ε at a distance r apart?
Answer» What is the magnitude of coulomb force between two charges placed in a medium of electrical permittivity ε at a distance r apart?

Discussion

5.	2 planets 'Xargonia' and 'Olfuba' have taken keen interest in our star 'The Sun'. They are observing our sun from the observatories built on their planet. Xargonia is 1 Light year away and the aperture area of its telescope is 1m2, while Olfuba is 2 Light years away and the aperture area of its telescope is 4m2. Find out whose telescope receives more energy? (Assume the Sun radiates E joules of energy per sec.)
Answer» 2 planets 'Xargonia' and 'Olfuba' have taken keen interest in our star 'The Sun'. They are observing our sun from the observatories built on their planet. Xargonia is 1 Light year away and the aperture area of its telescope is $1 m^{2}$ , while Olfuba is 2 Light years away and the aperture area of its telescope is $4 m^{2}$ . Find out whose telescope receives more energy? (Assume the Sun radiates E joules of energy per sec.)

5.

2 planets 'Xargonia' and 'Olfuba' have taken keen interest in our star 'The Sun'. They are observing our sun from the observatories built on their planet. Xargonia is 1 Light year away and the aperture area of its telescope is 1m2, while Olfuba is 2 Light years away and the aperture area of its telescope is 4m2. Find out whose telescope receives more energy? (Assume the Sun radiates E joules of energy per sec.)

Answer»

2 planets 'Xargonia' and 'Olfuba' have taken keen interest in our star 'The Sun'. They are observing our sun from the observatories built on their planet.

Xargonia is 1 Light year away and the aperture area of its telescope is $1 m^{2}$ , while Olfuba is 2 Light years away and the aperture area of its telescope is $4 m^{2}$ .

Find out whose telescope receives more energy? (Assume the Sun radiates E joules of energy per sec.)

Discussion

6.	A particle projected from point O with velocity u in a direction making an angle α with the horizontal. At any instant its position is at point P at right angles to the initial direction of projection. Its velocity at point O is
Answer» A particle projected from point O with velocity u in a direction making an angle $α$ with the horizontal. At any instant its position is at point P at right angles to the initial direction of projection. Its velocity at point O is

6.

A particle projected from point O with velocity u in a direction making an angle α with the horizontal. At any instant its position is at point P at right angles to the initial direction of projection. Its velocity at point O is

Answer»

A particle projected from point O with velocity u in a direction making an angle $α$ with the horizontal. At any instant its position is at point P at right angles to the initial direction of projection. Its velocity at point O is

Discussion

7.	Estimate the proportion of boron impurity which will increase the conductivity of a pure silicon sample by a factor of 100. Assume that each boron atom creates a hole and the concentration of holes in pure silicon at the same temperature is 7×1015 holes per cubic metre. Density of silicon is 5×1028 atoms per cubic metre.
Answer» Estimate the proportion of boron impurity which will increase the conductivity of a pure silicon sample by a factor of 100. Assume that each boron atom creates a hole and the concentration of holes in pure silicon at the same temperature is $7 \times 10^{15}$ holes per cubic metre. Density of silicon is $5 \times 10^{28}$ atoms per cubic metre.

Discussion

8.	A rectangular loop of sides 20 cm an 10 cm carries a current of 5.0 A. A uniform magnetic field of magnitude 0.20 T exists parallel to the longer side of the loop. (a) what is the force acting on the loop ? (b) What is the torque acting on the loop ?
Answer» A rectangular loop of sides 20 cm an 10 cm carries a current of 5.0 A. A uniform magnetic field of magnitude 0.20 T exists parallel to the longer side of the loop. (a) what is the force acting on the loop ? (b) What is the torque acting on the loop ?

Discussion

9.	An aeroplane has to go along straight line from A to B and back along. The relative speed w.r.t. wind is V. The wind blows perpendicular to line AB with speed Vo. The distance between A & B is l. The total time for the round trip is
Answer» An aeroplane has to go along straight line from $A$ to $B$ and back along. The relative speed w.r.t. wind is $V$ . The wind blows perpendicular to line $A B$ with speed $V_{o}$ . The distance between $A$ & $B$ is $l$ . The total time for the round trip is

Discussion

10.	Two rods of lengths l1 and l2 are made of materials whose coefficients of linear expansion are α1 and α2. If the difference between the two lengths is independent of temperature, then
Answer» Two rods of lengths $l_{1}$ and $l_{2}$ are made of materials whose coefficients of linear expansion are $α_{1}$ and $α_{2}$ . If the difference between the two lengths is independent of temperature, then

Discussion

11.	When the displacement is half the amplitude, the ratio of potential energy to the total energy is
Answer» When the displacement is half the amplitude, the ratio of potential energy to the total energy is

11.

When the displacement is half the amplitude, the ratio of potential energy to the total energy is

Answer»

When the displacement is half the amplitude, the ratio of potential energy to the total energy is

Discussion

12.	Figure (35-E4) shows a long wire bent at the middle to form a right angle.Show that the magnitudes of the magnetic fields at the points P,Q,R and S are equal and find this magnitude.
Answer» Figure (35-E4) shows a long wire bent at the middle to form a right angle.Show that the magnitudes of the magnetic fields at the points P,Q,R and S are equal and find this magnitude.

12.

Figure (35-E4) shows a long wire bent at the middle to form a right angle.Show that the magnitudes of the magnetic fields at the points P,Q,R and S are equal and find this magnitude.

Answer»

Figure (35-E4) shows a long wire bent at the middle to form a right angle.Show that the magnitudes of the magnetic fields at the points P,Q,R and S are equal and find this magnitude.

Discussion

13.	Light from a point source falls on a small area placed perpendicular to the incident light. If the area is rotated about the incident light by an angle of 60∘, by what fraction wil the illuminance change?
Answer» Light from a point source falls on a small area placed perpendicular to the incident light. If the area is rotated about the incident light by an angle of $60^{\circ}$ , by what fraction wil the illuminance change?

Discussion

14.	Find the energy stored in a 60 cm length of a laser beam operating at 4 mW.
Answer» Find the energy stored in a $60 cm$ length of a laser beam operating at $4 mW$ .

Discussion

15.	A wave pulse is travelling on a string with a speed v towards the positive X-axis. The shape of the string at t = 0 is given by g(x)=A sin(xa), where A and a are constants. (a) What are the dimensions of A and a ? (b) Write the equation of the wave for a general time t, if the wave speed is v.
Answer» A wave pulse is travelling on a string with a speed v towards the positive X-axis. The shape of the string at t = 0 is given by $g (x) = A s i n (\frac{x}{a})$ , where A and a are constants. (a) What are the dimensions of A and a ? (b) Write the equation of the wave for a general time t, if the wave speed is v.

Discussion

16.	Which of the following devices measures current?
Answer» Which of the following devices measures current?

Discussion

17.	An air bubble in sphere having 4 cm diameter appears 1 cm from surface nearest to eye when looked along diameter. If amg = 1.5, the distance of bubble from refracting surface is [CPMT 2002]
Answer» An air bubble in sphere having 4 cm diameter appears 1 cm from surface nearest to eye when looked along diameter. If _am_g = 1.5, the distance of bubble from refracting surface is [CPMT 2002]

17.

An air bubble in sphere having 4 cm diameter appears 1 cm from surface nearest to eye when looked along diameter. If amg = 1.5, the distance of bubble from refracting surface is [CPMT 2002]

Answer»

An air bubble in sphere having 4 cm diameter appears 1 cm from surface nearest to eye when looked along diameter. If _am_g = 1.5, the distance of bubble from refracting surface is

[CPMT 2002]

Discussion

18.	What may be the correct orbital notation if the wave function is −Ψ=181√6π(1a0)32 σeσ3(3cos2θ−1);Here σ=r/a0 and a0=h2ϵ0πme2
Answer» What may be the correct orbital notation if the wave function is $- Ψ = \frac{1}{81 \sqrt{6 π}} (\frac{1}{a_{0}}) \frac{3}{2} σ e^{\frac{σ}{3}} (3 c o s^{2} θ - 1); H e r e σ = r / a_{0} a n d a_{0} = \frac{h^{2} ϵ_{0}}{π m e^{2}}$

Discussion

19.	The time taken by a photoelectron to come out after the photon strikes is approximately
Answer» The time taken by a photoelectron to come out after the photon strikes is approximately

Discussion

20.	A Carnot engine working between 300K and 600K has work output of 800 J per cycle. What is amount of heat energy supplied to the engine from source per cycle
Answer» A Carnot engine working between 300K and 600K has work output of 800 J per cycle. What is amount of heat energy supplied to the engine from source per cycle

Discussion

21.	The reading of the spring balance for the system shown in the figure is (in kg). The elevator is going up with an acceleration of g10 m/s2. (Take g=10 m/s2)
Answer» The reading of the spring balance for the system shown in the figure is (in $k g$ ). The elevator is going up with an acceleration of $\frac{g}{10} m / s^{2}$ . (Take $g = 10 m / s^{2}$ )

Discussion

22.	Indian style of cooling drinking water is to keep it in a pitcher having porous walls. Water comes to the outer surface very slowly and evaporates. Most of the energy needed for is taken from the water itself and the water is cooled down. If pitcher has 10 kg of water, find the time in which the temperature of water falls by 5∘C. The approximate rate of vaporisation is 5 g min−1 (Cw=1 cal/g-∘C, Lv=540 cal/g)
Answer» Indian style of cooling drinking water is to keep it in a pitcher having porous walls. Water comes to the outer surface very slowly and evaporates. Most of the energy needed for is taken from the water itself and the water is cooled down. If pitcher has $10 kg$ of water, find the time in which the temperature of water falls by $5^{\circ} C$ . The approximate rate of vaporisation is $5 {g min}^{- 1}$ $(C_{w} = 1 {cal/g-}^{\circ} C, L_{v} = 540 cal/g)$

Discussion

23.	The energy of hydrogen atom in nth orbit is En, then the energy in nth orbit of singly ionised helium atom will be
Answer» The energy of hydrogen atom in nth orbit is $E_{n}$ , then the energy in nth orbit of singly ionised helium atom will be

Discussion

24.	An iron ball and a wooden ball of the same radius are released from a height 'h' in vacuum. The time taken by both of them to reach the ground is
Answer» An iron ball and a wooden ball of the same radius are released from a height 'h' in vacuum. The time taken by both of them to reach the ground is

Discussion

25.	Two wires of the same material (Young’s modulus Y) and same length L but radii R and 2R respectively are joined end to end and a weight w is suspended from the combination as shown in the figure. The elastic potential energy in the system is
Answer» Two wires of the same material (Young’s modulus $Y$ ) and same length $L$ but radii $R$ and $2 R$ respectively are joined end to end and a weight $w$ is suspended from the combination as shown in the figure. The elastic potential energy in the system is

Discussion

26.	A winding wire which is used to frame a solenoid can bear a maximum 10 A current. If length of solenoid is 80cm and it's cross sectional radius is 3 cm then required length of winding wire is (B=0.2T)
Answer» A winding wire which is used to frame a solenoid can bear a maximum 10 A current. If length of solenoid is 80cm and it's cross sectional radius is 3 cm then required length of winding wire is (B=0.2T)

Discussion

27.	A hollow metallic sphere of radius 20 cm surrounds a concentric metallic sphere of radius 5 cm. The space between the two spheres is filled with a nonmetallic material. The inner and outer spheres are maintained at 50∘C and 10∘C respectively and it is found that 100 J of heat second. Find the thermal conductivity of the material between the spheres.
Answer» A hollow metallic sphere of radius 20 cm surrounds a concentric metallic sphere of radius 5 cm. The space between the two spheres is filled with a nonmetallic material. The inner and outer spheres are maintained at $50^{\circ} C$ and $10^{\circ} C$ respectively and it is found that 100 J of heat second. Find the thermal conductivity of the material between the spheres.

Discussion

28.	A tuning fork vibrates at 260 Hz. Find the length of the shortest closed organ pipe that will resonate with the tuning fork. Given, speed of sound in air is 340 m/s.
Answer» A tuning fork vibrates at $260 Hz$ . Find the length of the shortest closed organ pipe that will resonate with the tuning fork. Given, speed of sound in air is $340 m/s$ .

Discussion

29.	The balloon, the light rope and the monkey shown in figure are at rest in the air. If the monkey reaches the top of the rope , by what distance does the ballon descent? Mass of the balloon = M , mass of the monkey = m and the lenght of the rope ascended by the monkey = L.
Answer» The balloon, the light rope and the monkey shown in figure are at rest in the air. If the monkey reaches the top of the rope , by what distance does the ballon descent? Mass of the balloon = M , mass of the monkey = m and the lenght of the rope ascended by the monkey = L.

29.

The balloon, the light rope and the monkey shown in figure are at rest in the air. If the monkey reaches the top of the rope , by what distance does the ballon descent? Mass of the balloon = M , mass of the monkey = m and the lenght of the rope ascended by the monkey = L.

Answer»

The balloon, the light rope and the monkey shown in figure are at rest in the air. If the monkey reaches the top of the rope , by what distance does the ballon descent? Mass of the balloon = M , mass of the monkey = m and the lenght of the rope ascended by the monkey = L.

Discussion

30.	A clock with a metal pendulum beating seconds keeps correct time at 0∘C. If it loses 12.5 seconds a day at 25∘C, the coefficient of linear expansion of metal of pendulum is
Answer» A clock with a metal pendulum beating seconds keeps correct time at $0^{\circ} C .$ If it loses 12.5 seconds a day at $25^{\circ} C,$ the coefficient of linear expansion of metal of pendulum is

Discussion

31.	The graph between u and v for a convex mirror is
Answer» The graph between u and v for a convex mirror is

31.

The graph between u and v for a convex mirror is

Answer»

The graph between u and v for a convex mirror is

Discussion

32.	As shown in the figure, water squirts horizontally out of two small holes in the side of cylinder and the two streams strike the ground at the same point. If the level of water stands at height H=4.25 m and hole P is at depth of 0.25 m below the surface of water, then find the depth of hole Q from the surface of water.
Answer» As shown in the figure, water squirts horizontally out of two small holes in the side of cylinder and the two streams strike the ground at the same point. If the level of water stands at height $H = 4.25 m$ and hole $P$ is at depth of $0.25 m$ below the surface of water, then find the depth of hole $Q$ from the surface of water.

Discussion

33.	The tungsten filament of an electric lamp has a surface area A and a power rating P. If the emissivity of the filament is ϵ and σ is Stefan’s constant, the steady temperature of the filament will be
Answer» The tungsten filament of an electric lamp has a surface area A and a power rating P. If the emissivity of the filament is $ϵ$ and $σ$ is Stefan’s constant, the steady temperature of the filament will be

Discussion

34.	6)The vapour density of PCI5 is 104.16, but when heated at 2300C, its vapour density is reduced to 62. The percentage of dissociation of PCI5 at this temperature will be:
Answer» 6)The vapour density of PCI₅ is 104.16, but when heated at 230⁰C, its vapour density is reduced to 62. The percentage of dissociation of PCI₅ at this temperature will be:

Discussion

35.	The rise of the water level in a capillary tube of radius 0.07 cm when dipped vertically in a beaker containing water (assuming it to be perfectly wetting) will be. Given : Surface tension of water is 0.07 Nm−1 and g=10 ms−2
Answer» The rise of the water level in a capillary tube of radius $0.07 cm$ when dipped vertically in a beaker containing water (assuming it to be perfectly wetting) will be. Given : Surface tension of water is $0.07 {Nm}^{- 1}$ and $g = 10 {ms}^{- 2}$

Discussion

36.	Electric field is directed towards
Answer» Electric field is directed towards

Discussion

37.	A wheel of radius 1 meter rolls forward half a revolution on a horizontal ground. The magnitude of the displacement of the point of the wheel initially in contact with the ground is
Answer» A wheel of radius 1 meter rolls forward half a revolution on a horizontal ground. The magnitude of the displacement of the point of the wheel initially in contact with the ground is

Discussion

38.	Why the small size of the cation leads to greater polarising power and why large charge on the cation leads to greater polarising power
Answer» Why the small size of the cation leads to greater polarising power and why large charge on the cation leads to greater polarising power

Discussion

39.	Figure below represents a Carnot engine that works between temperatures T1 400 K and T2 150 K and drives aCarnot refrigerator that works between temperatures T3 325 K and T4 225 K.What is the ratio Q3Q1?
Answer» Figure below represents a Carnot engine that works between temperatures $T_{1}$ 400 K and $T_{2}$ 150 K and drives aCarnot refrigerator that works between temperatures $T_{3}$ 325 K and $T_{4}$ 225 K.What is the ratio $\frac{Q 3}{Q 1}$ ?

39.

Figure below represents a Carnot engine that works between temperatures T1 400 K and T2 150 K and drives aCarnot refrigerator that works between temperatures T3 325 K and T4 225 K.What is the ratio Q3Q1?

Answer»

Figure below represents a Carnot engine that works between temperatures $T_{1}$ 400 K and $T_{2}$ 150 K and drives aCarnot refrigerator that works between temperatures $T_{3}$ 325 K and $T_{4}$ 225 K.What is the ratio $\frac{Q 3}{Q 1}$ ?

Discussion

40.	A boy stands straight in front of a mirror at a distance of 30cm away from it. He sees his erect image whose height is of his real height. The mirror he is using is [MP PMT 1993]
Answer» A boy stands straight in front of a mirror at a distance of 30cm away from it. He sees his erect image whose height is of his real height. The mirror he is using is [MP PMT 1993]

40.

A boy stands straight in front of a mirror at a distance of 30cm away from it. He sees his erect image whose height is of his real height. The mirror he is using is [MP PMT 1993]

Answer»

A boy stands straight in front of a mirror at a distance of 30cm away from it.

He sees his erect image whose height is of his real height. The mirror he is using is

[MP PMT 1993]

Discussion

41.	As the temperature increases, the average kinetic energy of molecules increases. What would be the effect of an increase of temperature on pressure provided the volume is constant? (a) Increases (b) Decreases (c) Remains same (d) Becomes half
Answer» As the temperature increases, the average kinetic energy of molecules increases. What would be the effect of an increase of temperature on pressure provided the volume is constant? (a) Increases (b) Decreases (c) Remains same (d) Becomes half

41.

As the temperature increases, the average kinetic energy of molecules increases. What would be the effect of an increase of temperature on pressure provided the volume is constant? (a) Increases (b) Decreases (c) Remains same (d) Becomes half

Answer»

As the temperature increases, the average kinetic energy of molecules increases. What would be the effect of an increase of temperature on pressure provided the volume is constant?

(a) Increases (b) Decreases

(c) Remains same (d) Becomes half

Discussion

42.	A capacitor stores charge Q at a potential difference V. If the voltage applied by a battery to the capacitor is doubled to 2V, then
Answer» A capacitor stores charge Q at a potential difference V. If the voltage applied by a battery to the capacitor is doubled to 2V, then

Discussion

43.	Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon [DCE 2000; 01]
Answer» Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon [DCE 2000; 01]

43.

Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon [DCE 2000; 01]

Answer»

Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon

[DCE 2000; 01]

Discussion

44.	A silver ingot weighing 2.1 kg is held by a string so as to be completely immersed in a liquid of relative density 0.8. The relative density of silver is 10.5. The tension in the string in kg-wt is
Answer» A silver ingot weighing 2.1 kg is held by a string so as to be completely immersed in a liquid of relative density 0.8. The relative density of silver is 10.5. The tension in the string in kg-wt is

Discussion

45.	Three resonant frequencies of a string are 90, 150 and 210 Hz. (i) Find the highest possible fundamental frequency of vibration of this string (ii) Which harmonics of the fundamental are the given frequencies? (iii) Which overtones are these frequencies?
Answer» Three resonant frequencies of a string are 90, 150 and 210 Hz. (i) Find the highest possible fundamental frequency of vibration of this string (ii) Which harmonics of the fundamental are the given frequencies? (iii) Which overtones are these frequencies?

45.

Three resonant frequencies of a string are 90, 150 and 210 Hz. (i) Find the highest possible fundamental frequency of vibration of this string (ii) Which harmonics of the fundamental are the given frequencies? (iii) Which overtones are these frequencies?

Answer»

Three resonant frequencies of a string are 90, 150 and 210 Hz.

(i) Find the highest possible fundamental frequency of vibration of this string

(ii) Which harmonics of the fundamental are the given frequencies?

(iii) Which overtones are these frequencies?

Discussion

46.	A Young’s double slit interference arrangement with slits S1 andS2is immersed in water (refractive index = 43) as shown in the figure. The position of maxima on the surface of water are given by x2=p2m2λ2−d2, where λ is the wavelength of light in air (refractive index = 1), 2d is the separation between the slits and m is an integer. The value of p is
Answer» A Young’s double slit interference arrangement with slits $S_{1}$ and $S_{2}$ is immersed in water (refractive index = $\frac{4}{3})$ as shown in the figure. The position of maxima on the surface of water are given by $x^{2} = p^{2} m^{2} λ^{2} - d^{2},$ where $λ$ is the wavelength of light in air (refractive index = 1), 2d is the separation between the slits and m is an integer. The value of p is

Discussion

47.	How should people wearing spectacles work with a microscope
Answer» How should people wearing spectacles work with a microscope

Discussion

48.	If the focal length of objective and eye lens are 1.2 cm and 3 cm respectively and the object is put 1.25 cm away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope is
Answer» If the focal length of objective and eye lens are 1.2 cm and 3 cm respectively and the object is put 1.25 cm away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope is

48.

If the focal length of objective and eye lens are 1.2 cm and 3 cm respectively and the object is put 1.25 cm away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope is

Answer»

If the focal length of objective and eye lens are 1.2 cm and 3 cm respectively

and the object is put 1.25 cm away from the objective lens and the final

image is formed at infinity. The magnifying power of the microscope is

Discussion

49.	Two transparent mediums of refractive indices μ1 and mu3 have a solid lens shaped transparent material of refractive index μ2 between them as shown in figures. A ray traversing these mediums is also shown in the figures. Column I, Column II and Column III represent different relationship among refractive index (μ), wavelength of light (λ) and velocity of light (v) in 3 different media. Column IColumn IIColumn III(I)μ1>μ2(i)λ2>λ3(P)v2>v1(II)μ3>μ2(ii)λ1=λ3(Q)v2=v3(III)μ1>μ3(iii)λ1<λ2(R)v3<v2(IV)μ2>μ3(iv)λ2<λ3(S)v1=v3 Which of the combination is correct for figure 1?
Answer» Two transparent mediums of refractive indices $μ_{1}$ and $m u_{3}$ have a solid lens shaped transparent material of refractive index $μ_{2}$ between them as shown in figures. A ray traversing these mediums is also shown in the figures. Column I, Column II and Column III represent different relationship among refractive index $(μ)$ , wavelength of light $(λ)$ and velocity of light (v) in 3 different media. $\begin{matrix} C o l u m n I & C o l u m n I I & C o l u m n I I I (I) & μ_{1} > μ_{2} & (i) & λ_{2} > λ_{3} & (P) & v_{2} > v_{1} (I I) & μ_{3} > μ_{2} & (i i) & λ_{1} = λ_{3} & (Q) & v_{2} = v_{3} (I I I) & μ_{1} > μ_{3} & (i i i) & λ_{1} < λ_{2} & (R) & v_{3} < v_{2} (I V) & μ_{2} > μ_{3} & (i v) & λ_{2} < λ_{3} & (S) & v_{1} = v_{3} \end{matrix}$ Which of the combination is correct for figure 1?

Discussion

50.	Two electric bulbs one of 200V-40W and other of 200V-100W are connected in series to a 200 volt line, then
Answer» Two electric bulbs one of 200V-40W and other of 200V-100W are connected in series to a 200 volt line, then

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

A uniform circular disc of mass 1 kg and radius 0.5 m is rotating about its axis with a constant angular velocity 5 rad/sec. Two birds, each of mass 0.25 kg sit gently at the opposite ends of the diameter of the disc. The final angular velocity of the disc will be

The wave number of the energy emitted when electron comes from fourth orbit to second orbit in hydrogen is 20,397 cm−1. The wave number of the energy for the same transition in He+ is

What is the magnitude of coulomb force between two charges placed in a medium of electrical permittivity ε at a distance r apart?

A particle projected from point O with velocity u in a direction making an angle α with the horizontal. At any instant its position is at point P at right angles to the initial direction of projection. Its velocity at point O is

A rectangular loop of sides 20 cm an 10 cm carries a current of 5.0 A. A uniform magnetic field of magnitude 0.20 T exists parallel to the longer side of the loop. (a) what is the force acting on the loop ? (b) What is the torque acting on the loop ?

An aeroplane has to go along straight line from A to B and back along. The relative speed w.r.t. wind is V. The wind blows perpendicular to line AB with speed Vo. The distance between A &amp; B is l. The total time for the round trip is

Two rods of lengths l1 and l2 are made of materials whose coefficients of linear expansion are α1 and α2. If the difference between the two lengths is independent of temperature, then

When the displacement is half the amplitude, the ratio of potential energy to the total energy is

Figure (35-E4) shows a long wire bent at the middle to form a right angle.Show that the magnitudes of the magnetic fields at the points P,Q,R and S are equal and find this magnitude.

Light from a point source falls on a small area placed perpendicular to the incident light. If the area is rotated about the incident light by an angle of 60∘, by what fraction wil the illuminance change?

Find the energy stored in a 60 cm length of a laser beam operating at 4 mW.

A wave pulse is travelling on a string with a speed v towards the positive X-axis. The shape of the string at t = 0 is given by g(x)=A sin(xa), where A and a are constants. (a) What are the dimensions of A and a ? (b) Write the equation of the wave for a general time t, if the wave speed is v.

Which of the following devices measures current?

An air bubble in sphere having 4 cm diameter appears 1 cm from surface nearest to eye when looked along diameter. If amg = 1.5, the distance of bubble from refracting surface is [CPMT 2002]

What may be the correct orbital notation if the wave function is −Ψ=181√6π(1a0)32 σeσ3(3cos2θ−1);Here σ=r/a0 and a0=h2ϵ0πme2

The time taken by a photoelectron to come out after the photon strikes is approximately

A Carnot engine working between 300K and 600K has work output of 800 J per cycle. What is amount of heat energy supplied to the engine from source per cycle

The reading of the spring balance for the system shown in the figure is (in kg). The elevator is going up with an acceleration of g10 m/s2. (Take g=10 m/s2)

The energy of hydrogen atom in nth orbit is En, then the energy in nth orbit of singly ionised helium atom will be

An iron ball and a wooden ball of the same radius are released from a height 'h' in vacuum. The time taken by both of them to reach the ground is

Two wires of the same material (Young’s modulus Y) and same length L but radii R and 2R respectively are joined end to end and a weight w is suspended from the combination as shown in the figure. The elastic potential energy in the system is

A winding wire which is used to frame a solenoid can bear a maximum 10 A current. If length of solenoid is 80cm and it's cross sectional radius is 3 cm then required length of winding wire is (B=0.2T)

A tuning fork vibrates at 260 Hz. Find the length of the shortest closed organ pipe that will resonate with the tuning fork. Given, speed of sound in air is 340 m/s.

The balloon, the light rope and the monkey shown in figure are at rest in the air. If the monkey reaches the top of the rope , by what distance does the ballon descent? Mass of the balloon = M , mass of the monkey = m and the lenght of the rope ascended by the monkey = L.

A clock with a metal pendulum beating seconds keeps correct time at 0∘C. If it loses 12.5 seconds a day at 25∘C, the coefficient of linear expansion of metal of pendulum is

The graph between u and v for a convex mirror is

The tungsten filament of an electric lamp has a surface area A and a power rating P. If the emissivity of the filament is ϵ and σ is Stefan’s constant, the steady temperature of the filament will be

6)The vapour density of PCI5 is 104.16, but when heated at 2300C, its vapour density is reduced to 62. The percentage of dissociation of PCI5 at this temperature will be:

The rise of the water level in a capillary tube of radius 0.07 cm when dipped vertically in a beaker containing water (assuming it to be perfectly wetting) will be. Given : Surface tension of water is 0.07 Nm−1 and g=10 ms−2

Electric field is directed towards

A wheel of radius 1 meter rolls forward half a revolution on a horizontal ground. The magnitude of the displacement of the point of the wheel initially in contact with the ground is

Why the small size of the cation leads to greater polarising power and why large charge on the cation leads to greater polarising power

Figure below represents a Carnot engine that works between temperatures T1 400 K and T2 150 K and drives aCarnot refrigerator that works between temperatures T3 325 K and T4 225 K.What is the ratio Q3Q1?

A boy stands straight in front of a mirror at a distance of 30cm away from it. He sees his erect image whose height is of his real height. The mirror he is using is [MP PMT 1993]

As the temperature increases, the average kinetic energy of molecules increases. What would be the effect of an increase of temperature on pressure provided the volume is constant? (a) Increases (b) Decreases (c) Remains same (d) Becomes half

A capacitor stores charge Q at a potential difference V. If the voltage applied by a battery to the capacitor is doubled to 2V, then

Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon [DCE 2000; 01]

A silver ingot weighing 2.1 kg is held by a string so as to be completely immersed in a liquid of relative density 0.8. The relative density of silver is 10.5. The tension in the string in kg-wt is

Three resonant frequencies of a string are 90, 150 and 210 Hz. (i) Find the highest possible fundamental frequency of vibration of this string (ii) Which harmonics of the fundamental are the given frequencies? (iii) Which overtones are these frequencies?

How should people wearing spectacles work with a microscope

If the focal length of objective and eye lens are 1.2 cm and 3 cm respectively and the object is put 1.25 cm away from the objective lens and the final image is formed at infinity. The magnifying power of the microscope is

Two electric bulbs one of 200V-40W and other of 200V-100W are connected in series to a 200 volt line, then

An aeroplane has to go along straight line from A to B and back along. The relative speed w.r.t. wind is V. The wind blows perpendicular to line AB with speed Vo. The distance between A & B is l. The total time for the round trip is