50278 + Interview Questions in Physics

1.	What will be the depth of object 'O' for an observer just below the interface CD? (μ3>μ2>μ1)
Answer» What will be the depth of object 'O' for an observer just below the interface CD? $(μ_{3} > μ_{2} > μ_{1})$

Discussion

2.	A water cooler of storage capacity 120 litres can cool water at a constant rate of P with in a closed circulation system (as shown schematically in the figure), the water from the cooler is used to cool an external device that generates constantly 3 kW of heat (thermal load). The temperature of water fed into the device cannot exceed 30oC and the entire stored 120 litres of water is initially cooled to 10oC. The entire system is thermally insulated. The minimum value of P (in watts) for which the device can be operated for 3 hours is(Specific heat of water is 4.2 kJ kg−1 K−1 and density of water is 1000 kg m−3)
Answer» A water cooler of storage capacity $120$ litres can cool water at a constant rate of $P$ with in a closed circulation system (as shown schematically in the figure), the water from the cooler is used to cool an external device that generates constantly $3 k W$ of heat (thermal load). The temperature of water fed into the device cannot exceed $30^{o} C$ and the entire stored $120$ litres of water is initially cooled to $10^{o} C$ . The entire system is thermally insulated. The minimum value of $P$ (in watts) for which the device can be operated for $3$ hours is (Specific heat of water is $4.2 k J$ ${k g}^{- 1}$ $K^{- 1}$ and density of water is $1000 k g$ $m^{- 3}$ )

Discussion

3.	The centripetal force on a satellite revolving around the earth is F. The gravitational force of the earth is also F. The net force on the satellite is
Answer» The centripetal force on a satellite revolving around the earth is F. The gravitational force of the earth is also F. The net force on the satellite is

Discussion

4.	For two resistor R1 and R2 connected in parallel the relative error in their equivalent resistance is {where R1 = (10.0 +- 0.1) and R2 = (20.0 +- 0.4)} a) 0.08 b) 0.05 c) 0.01 d) 0.04
Answer» For two resistor R1 and R2 connected in parallel the relative error in their equivalent resistance is {where R1 = (10.0 +- 0.1) and R2 = (20.0 +- 0.4)} a) 0.08 b) 0.05 c) 0.01 d) 0.04

Discussion

5.	5 kJ of heat required to raise the temperature of 10 moles of a gas by 100∘C, at a constant volume. The specific heat capacity of the gas is (J/ mol-K)
Answer» $5 kJ$ of heat required to raise the temperature of $10 moles$ of a gas by $100^{\circ} C$ , at a constant volume. The specific heat capacity of the gas is $(J/ mol-K)$

Discussion

6.	A tank 5 metres height is filled with water and then is filled to the top with oil of density 0.85 gm/cm^3 the pressure at the bottom of the time due to these liquids is1)1.85 gram per CM square2) 89.2 5 gram per centimetre square3) 462.5 gram per centimetre square4)500 gram per centimetre square
Answer» A tank 5 metres height is filled with water and then is filled to the top with oil of density 0.85 gm/cm^3 the pressure at the bottom of the time due to these liquids is 1)1.85 gram per CM square 2) 89.2 5 gram per centimetre square 3) 462.5 gram per centimetre square 4)500 gram per centimetre square

Discussion

7.	94.A boy standing on a long railroad car throws a ball straight up with an accleration of 1m/s2 and the projection velocity in vertical direction is 9.8m/s. How far behind the boy will ball fall on the car.
Answer» 94.A boy standing on a long railroad car throws a ball straight up with an accleration of 1m/s2 and the projection velocity in vertical direction is 9.8m/s. How far behind the boy will ball fall on the car.

Discussion

8.	Two masses M and m are connected to the ends of a string passing over a smooth pulley. The tension in the string is T and the masses are moving with an acceleration a. If the masses are interchanged then what will be it's effect on a and T? Will they change
Answer» Two masses M and m are connected to the ends of a string passing over a smooth pulley. The tension in the string is T and the masses are moving with an acceleration a. If the masses are interchanged then what will be it's effect on a and T? Will they change

Discussion

9.	an object is placed in front of two convex lenses one by one a ta distance of u from the lens. The focal length of the lenses are 30cm and 15 cm respectively. If the size of image formed in the two cases is same then u isa) 15cm b) 20cm c) 25 cm d) 30 cm
Answer» an object is placed in front of two convex lenses one by one a ta distance of u from the lens. The focal length of the lenses are 30cm and 15 cm respectively. If the size of image formed in the two cases is same then u is a) 15cm b) 20cm c) 25 cm d) 30 cm

Discussion

10.	A series AC circuit containing an inductor (20 mH), a capacitor (120 μF) and a resistor (60 Ω) is driven by an AC source of 24 V, 50 Hz. The energy dissipated in the circuit in 60 sec is:
Answer» A series $AC$ circuit containing an inductor $(20 mH)$ , a capacitor $(120 μ F)$ and a resistor $(60 Ω)$ is driven by an $AC$ source of $24 V, 50 Hz$ . The energy dissipated in the circuit in $60 sec$ is:

Discussion

11.	In the figure shown below, a quarter ring of radius r is placed in the first quadrant of a cartesian co-ordinate system, with centre at origin. Find the co-ordinates of COM of the quarter ring.
Answer» In the figure shown below, a quarter ring of radius $r$ is placed in the first quadrant of a cartesian co-ordinate system, with centre at origin. Find the co-ordinates of $C O M$ of the quarter ring.

Discussion

12.	A vector has component along the x-axis equal to 25 unit and along the y-axis equal to 60 unit. The magnitude of the vector is
Answer» A vector has component along the $x$ -axis equal to $25 unit$ and along the $y$ -axis equal to $60 unit$ . The magnitude of the vector is

Discussion

13.	An air-cored solenoid of length 0.3 m, area of cross section 1.2×10−3 m2 has 2500 turns. Around its central section, a coil of 350 turns is wound. The solenoid and the coil are electrically insulated from each other. The magnitude of EMF induced in the coil , if the initial current of 3 A in the solenoid is reversed in 0.25 sec is
Answer» An air-cored solenoid of length $0.3 m$ , area of cross section $1.2 \times 10^{- 3} m^{2}$ has $2500 turns$ . Around its central section, a coil of $350 turns$ is wound. The solenoid and the coil are electrically insulated from each other. The magnitude of EMF induced in the coil , if the initial current of $3 A$ in the solenoid is reversed in $0.25 sec$ is

Discussion

14.	A particle is moving in a circle of radius R in such a way that at any instant the normal and tangential component of it's accelerations are equal. If it's speed at t=0 is v0. The time taken to complete the first revolution is
Answer» A particle is moving in a circle of radius $R$ in such a way that at any instant the normal and tangential component of it's accelerations are equal. If it's speed at $t = 0$ is $v_{0}$ . The time taken to complete the first revolution is

Discussion

15.	A particle of mass 5 kg is initially at rest. A force starts acting on it along a fixed direction. The magnitude of the force changes with time as shown in the figure. Find the velocity of the particle at the end of 20 s.
Answer» A particle of mass $5 kg$ is initially at rest. A force starts acting on it along a fixed direction. The magnitude of the force changes with time as shown in the figure. Find the velocity of the particle at the end of $20 s$ .

Discussion

16.	from a rifle of mass 4 kg ,a bullet of mass 50 g is fired with an initial velocity of 35 m/s calculate the initial recoil velocity of the rifle
Answer» from a rifle of mass 4 kg ,a bullet of mass 50 g is fired with an initial velocity of 35 m/s calculate the initial recoil velocity of the rifle

Discussion

17.	The displacement of a particle of mass 1 kg on a horizontal smooth surface is a function of time given by x=13t3. Find out the work done by the external agent for the first one second.
Answer» The displacement of a particle of mass 1 kg on a horizontal smooth surface is a function of time given by $x = \frac{1}{3} t^{3}$ . Find out the work done by the external agent for the first one second.

17.

The displacement of a particle of mass 1 kg on a horizontal smooth surface is a function of time given by x=13t3. Find out the work done by the external agent for the first one second.

Answer»

The displacement of a particle of mass 1 kg on a horizontal smooth surface is a function of time given by

$x = \frac{1}{3} t^{3}$ . Find out the work done by the external agent for the first one second.

Discussion

18.	A wave disturbance in a medium is described by y(x , t)= 0.02 cos (50 π t + π2) cos (10 πx) where x and y are in metre and t in second
Answer» A wave disturbance in a medium is described by y(x , t)= 0.02 cos (50 $π$ t + $\frac{π}{2}$ ) cos (10 $π$ x) where x and y are in metre and t in second

Discussion

19.	Add 000.0099 and 0.00007896 keeping in mind significant figures
Answer» Add 000.0099 and 0.00007896 keeping in mind significant figures

Discussion

20.	The time period of polar satellites is about (take g=9.8 ms−2 and radius of the EarthR=6.3×106 m),[Height of a polar satellite above earth's surface will be around 700 km]
Answer» The time period of polar satellites is about (take $g = 9.8 {ms}^{- 2}$ and radius of the Earth $R = 6.3 \times 10^{6} m$ ), [Height of a polar satellite above earth's surface will be around $700 km$ ]

Discussion

21.	The energy of emergent protons in MeV from a cyclotron having radius of its dees 1.8 m and applied magnetic field 0.7T is (mass of proton = 1.67×10^−27 kg):
Answer» The energy of emergent protons in MeV from a cyclotron having radius of its dees 1.8 m and applied magnetic field 0.7T is (mass of proton = 1.67×10^−27 kg):

Discussion

22.	Should I be perfect in Electrostatics to continue the Current Electricity? Or what is the pre-requisite of the Current Electricity?
Answer» Should I be perfect in Electrostatics to continue the Current Electricity? Or what is the pre-requisite of the Current Electricity?

Discussion

23.	The sum of the magnitudes of two forces acting at a point is 18 and the magnitude of their resultant is 12. If the resultant is at 90∘ with the force of smaller magnitude, then what are the magnitudes of the forces?
Answer» The sum of the magnitudes of two forces acting at a point is $18$ and the magnitude of their resultant is $12$ . If the resultant is at $90^{\circ}$ with the force of smaller magnitude, then what are the magnitudes of the forces?

Discussion

24.	A constant force −→F1=(2^i−4^j) N displaces a particle from (1,−1,2) to (−1,−1,3) and then another force of −→F2=(3^i+4^j) N, displaces it from (−1,−1,3) to (5,5,5) (displacements being measure in metre). Find the total work done.
Answer» A constant force $_{1} = (2^i - 4^j) N$ displaces a particle from $(1, - 1, 2)$ to $(- 1, - 1, 3)$ and then another force of $_{2} = (3^i + 4^j) N$ , displaces it from $(- 1, - 1, 3)$ to $(5, 5, 5)$ (displacements being measure in metre). Find the total work done.

Discussion

25.	in case of reflection of wave, the rigid boundary must have zero displacement what does it mean??
Answer» in case of reflection of wave, the rigid boundary must have zero displacement what does it mean??

Discussion

26.	The work function of a metal is hν0. Light of frequency ν falls on this metal. The photoelectric effect will take place only if ν ν0.
Answer» The work function of a metal is $h ν_{0}$ . Light of frequency $ν$ falls on this metal. The photoelectric effect will take place only if $ν$ $ν_{0}$ .

Discussion

27.	A sphere of radius R has a uniform distribution of electric charge in its volume. At a distance x(<R) from its centre, the electric field is directly proportional to
Answer» A sphere of radius $R$ has a uniform distribution of electric charge in its volume. At a distance $x (< R)$ from its centre, the electric field is directly proportional to

Discussion

28.	in a simple pendulum lenght increases by 4% and g increases by 2% then what will be thr changr in time perio
Answer» in a simple pendulum lenght increases by 4% and g increases by 2% then what will be thr changr in time perio

Discussion

29.	Two parallel rail tracks run north south. Train A moves north with a speed of 54 km/h and train B moves south with a speed of 90 km/h. What is the a)velocity of train B with respect to A b)velocity of ground with respect to ground. In the text book they are converting 54k km/h into 15 m/s and -90 km/h into -25 m/s. which method are they using. Please clear my doubt
Answer» Two parallel rail tracks run north south. Train A moves north with a speed of 54 km/h and train B moves south with a speed of 90 km/h. What is the a)velocity of train B with respect to A b)velocity of ground with respect to ground. In the text book they are converting 54k km/h into 15 m/s and -90 km/h into -25 m/s. which method are they using. Please clear my doubt

Discussion

30.	A wire is cut into 3 pieces, which are put together parallelly to obtain one conductor. If the original resistance of wire was R, the resistance of the new conductor will be
Answer» A wire is cut into 3 pieces, which are put together parallelly to obtain one conductor. If the original resistance of wire was $R$ , the resistance of the new conductor will be

Discussion

31.	The ratio of the weight of a man in a stationary lift and when it is moving downward with uniform acceleration ‘a’ is 3:2. The value of ‘a’ is (g – Acceleration due to gravity on the earth)
Answer» The ratio of the weight of a man in a stationary lift and when it is moving downward with uniform acceleration ‘a’ is 3:2. The value of ‘a’ is (g – Acceleration due to gravity on the earth)

Discussion

32.	A particle is moving with momentum p and kinetic energy K in a gravity free space. A constant force F (directed perpendicular to the initial momentum) now acts on the particle for time t. Final kinetic energy of the particle is
Answer» A particle is moving with momentum $p$ and kinetic energy $K$ in a gravity free space. A constant force $F$ (directed perpendicular to the initial momentum) now acts on the particle for time $t$ . Final kinetic energy of the particle is

Discussion

33.	Two circular loops of radii 0.05 m and 0.09 m are arranged such that their axes coincide and their centres are 0.12 m apart. Charge of 10−6 C is spread uniformly on each loop. The potential difference between the centres of the loops is
Answer» Two circular loops of radii $0.05 m$ and $0.09 m$ are arranged such that their axes coincide and their centres are $0.12 m$ apart. Charge of $10^{- 6} C$ is spread uniformly on each loop. The potential difference between the centres of the loops is

Discussion

34.	If Bohr’s quantisation postulate (angular momentum = nh/2π) is abasic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbitsof planets around the sun?
Answer» If Bohr’s quantisation postulate (angular momentum = nh/2π) is abasic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbitsof planets around the sun?

Discussion

35.	The number of rotational degree of freedom for a diatomic gas is
Answer» The number of rotational degree of freedom for a diatomic gas is

Discussion

36.	15. Why latis energy is inversly proportional to size
Answer» 15. Why latis energy is inversly proportional to size

Discussion

37.	In the given figure, the focal length of the two mirrors M−1 and M−2 for the given incident rays are f1 and f2 respectively, then :
Answer» In the given figure, the focal length of the two mirrors $M - 1$ and $M - 2$ for the given incident rays are $f_{1}$ and $f_{2}$ respectively, then :

Discussion

38.	Two coherent light sources having intensities in the ratio 2x produces an interference pattern. The ratio Imax−IminImax+Imin will be :
Answer» Two coherent light sources having intensities in the ratio $2 x$ produces an interference pattern. The ratio $\frac{I_{max} - I_{min}}{I_{max} + I_{min}}$ will be :

Discussion

39.	If the angles of dip at two different places are 30∘ and 45∘ respectively, then the ratio of horizontal components of earth's magnetic field at the two places will be
Answer» If the angles of dip at two different places are $30^{\circ}$ and $45^{\circ}$ respectively, then the ratio of horizontal components of earth's magnetic field at the two places will be

Discussion

40.	Represent point 3,-4,5 in unit vector representation.
Answer» Represent point 3,-4,5 in unit vector representation.

Discussion

41.	19. for given isotherms correct relationship between T1,T2,T3 is (a)T1>T2>T3 (b)T2>T3>T1 (c)T3>T2>T1 (d)T1>T3>T2
Answer» 19. for given isotherms correct relationship between T1,T2,T3 is (a)T1>T2>T3 (b)T2>T3>T1 (c)T3>T2>T1 (d)T1>T3>T2

Discussion

42.	Identify the correct statement from the following
Answer» Identify the correct statement from the following

Discussion

43.	The logic circuit shown above is equivalent to:
Answer» The logic circuit shown above is equivalent to:

Discussion

44.	What is acceleration of free tall
Answer» What is acceleration of free tall

Discussion

45.	In a 1D motion, ball B is ahead of A. Ball A is moving with a speed of 10 m/s towards B and ball B is moving with speed 15 m/s towards ball A. After the collision, ball A starts moving with a speed of 5 m/s towards ball B and ball B starts moving with a speed of 20 m/s away from A. Find the coefficient of restitution (e).
Answer» In a $1 D$ motion, ball $B$ is ahead of $A$ . Ball $A$ is moving with a speed of $10 m/s$ towards $B$ and ball $B$ is moving with speed $15 m/s$ towards ball $A$ . After the collision, ball $A$ starts moving with a speed of $5 m/s$ towards ball $B$ and ball $B$ starts moving with a speed of $20 m/s$ away from $A$ . Find the coefficient of restitution $(e)$ .

Discussion

46.	Three blocks A, B and C of masses 2 kg, 3 kg and4 kg are placed as shown. Coefficient of frictionbetween A and B is 0.5 and that between B and Cis0.1. The surface is frictionless. The maximum forceF that can be applied horizontally onto A such thatthe three blocks move together isA HAB= 0.5= 0.1F>ВuBcсПТFrictionlessLL
Answer» Three blocks A, B and C of masses 2 kg, 3 kg and4 kg are placed as shown. Coefficient of frictionbetween A and B is 0.5 and that between B and Cis0.1. The surface is frictionless. The maximum forceF that can be applied horizontally onto A such thatthe three blocks move together isA HAB= 0.5= 0.1F>ВuBcсПТFrictionlessLL

Discussion

47.	show that area under the velocity time graph of a body moving 1) uniformly and 2) with a constant acceleration is displacement
Answer» show that area under the velocity time graph of a body moving 1) uniformly and 2) with a constant acceleration is displacement

Discussion

48.	How to find formal charge of NO?
Answer» How to find formal charge of NO?

Discussion

49.	A man wants to cross the river to an exactly opposite point on the other bank. If he can row his boat with 2√3 times the velocity of the current, then at what angle to the current he must keep the boat pointed?
Answer» A man wants to cross the river to an exactly opposite point on the other bank. If he can row his boat with $\frac{2}{\sqrt{3}}$ times the velocity of the current, then at what angle to the current he must keep the boat pointed?

Discussion

50.	The wavelength of the first line in Balmer series in the hydrogen spectrum is λ. What is the wavelength of the second line?
Answer» The wavelength of the first line in Balmer series in the hydrogen spectrum is $λ$ . What is the wavelength of the second line?

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

What will be the depth of object 'O' for an observer just below the interface CD? (μ3&gt;μ2&gt;μ1)

The centripetal force on a satellite revolving around the earth is F. The gravitational force of the earth is also F. The net force on the satellite is

For two resistor R1 and R2 connected in parallel the relative error in their equivalent resistance is {where R1 = (10.0 +- 0.1) and R2 = (20.0 +- 0.4)} a) 0.08 b) 0.05 c) 0.01 d) 0.04

5 kJ of heat required to raise the temperature of 10 moles of a gas by 100∘C, at a constant volume. The specific heat capacity of the gas is (J/ mol-K)

A tank 5 metres height is filled with water and then is filled to the top with oil of density 0.85 gm/cm^3 the pressure at the bottom of the time due to these liquids is1)1.85 gram per CM square2) 89.2 5 gram per centimetre square3) 462.5 gram per centimetre square4)500 gram per centimetre square

94.A boy standing on a long railroad car throws a ball straight up with an accleration of 1m/s2 and the projection velocity in vertical direction is 9.8m/s. How far behind the boy will ball fall on the car.

Two masses M and m are connected to the ends of a string passing over a smooth pulley. The tension in the string is T and the masses are moving with an acceleration a. If the masses are interchanged then what will be it's effect on a and T? Will they change

an object is placed in front of two convex lenses one by one a ta distance of u from the lens. The focal length of the lenses are 30cm and 15 cm respectively. If the size of image formed in the two cases is same then u isa) 15cm b) 20cm c) 25 cm d) 30 cm

A series AC circuit containing an inductor (20 mH), a capacitor (120 μF) and a resistor (60 Ω) is driven by an AC source of 24 V, 50 Hz. The energy dissipated in the circuit in 60 sec is:

In the figure shown below, a quarter ring of radius r is placed in the first quadrant of a cartesian co-ordinate system, with centre at origin. Find the co-ordinates of COM of the quarter ring.

A vector has component along the x-axis equal to 25 unit and along the y-axis equal to 60 unit. The magnitude of the vector is

A particle is moving in a circle of radius R in such a way that at any instant the normal and tangential component of it's accelerations are equal. If it's speed at t=0 is v0. The time taken to complete the first revolution is

A particle of mass 5 kg is initially at rest. A force starts acting on it along a fixed direction. The magnitude of the force changes with time as shown in the figure. Find the velocity of the particle at the end of 20 s.

from a rifle of mass 4 kg ,a bullet of mass 50 g is fired with an initial velocity of 35 m/s calculate the initial recoil velocity of the rifle

The displacement of a particle of mass 1 kg on a horizontal smooth surface is a function of time given by x=13t3. Find out the work done by the external agent for the first one second.

A wave disturbance in a medium is described by y(x , t)= 0.02 cos (50 π t + π2) cos (10 πx) where x and y are in metre and t in second

Add 000.0099 and 0.00007896 keeping in mind significant figures

The time period of polar satellites is about (take g=9.8 ms−2 and radius of the EarthR=6.3×106 m),[Height of a polar satellite above earth's surface will be around 700 km]

The energy of emergent protons in MeV from a cyclotron having radius of its dees 1.8 m and applied magnetic field 0.7T is (mass of proton = 1.67×10^−27 kg):

Should I be perfect in Electrostatics to continue the Current Electricity? Or what is the pre-requisite of the Current Electricity?

The sum of the magnitudes of two forces acting at a point is 18 and the magnitude of their resultant is 12. If the resultant is at 90∘ with the force of smaller magnitude, then what are the magnitudes of the forces?

A constant force −→F1=(2^i−4^j) N displaces a particle from (1,−1,2) to (−1,−1,3) and then another force of −→F2=(3^i+4^j) N, displaces it from (−1,−1,3) to (5,5,5) (displacements being measure in metre). Find the total work done.

in case of reflection of wave, the rigid boundary must have zero displacement what does it mean??

The work function of a metal is hν0. Light of frequency ν falls on this metal. The photoelectric effect will take place only if ν ν0.

A sphere of radius R has a uniform distribution of electric charge in its volume. At a distance x(&lt;R) from its centre, the electric field is directly proportional to

in a simple pendulum lenght increases by 4% and g increases by 2% then what will be thr changr in time perio

A wire is cut into 3 pieces, which are put together parallelly to obtain one conductor. If the original resistance of wire was R, the resistance of the new conductor will be

The ratio of the weight of a man in a stationary lift and when it is moving downward with uniform acceleration ‘a’ is 3:2. The value of ‘a’ is (g – Acceleration due to gravity on the earth)

A particle is moving with momentum p and kinetic energy K in a gravity free space. A constant force F (directed perpendicular to the initial momentum) now acts on the particle for time t. Final kinetic energy of the particle is

Two circular loops of radii 0.05 m and 0.09 m are arranged such that their axes coincide and their centres are 0.12 m apart. Charge of 10−6 C is spread uniformly on each loop. The potential difference between the centres of the loops is

If Bohr’s quantisation postulate (angular momentum = nh/2π) is abasic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbitsof planets around the sun?

The number of rotational degree of freedom for a diatomic gas is

15. Why latis energy is inversly proportional to size

In the given figure, the focal length of the two mirrors M−1 and M−2 for the given incident rays are f1 and f2 respectively, then :

Two coherent light sources having intensities in the ratio 2x produces an interference pattern. The ratio Imax−IminImax+Imin will be :

If the angles of dip at two different places are 30∘ and 45∘ respectively, then the ratio of horizontal components of earth's magnetic field at the two places will be

Represent point 3,-4,5 in unit vector representation.

19. for given isotherms correct relationship between T1,T2,T3 is (a)T1>T2>T3 (b)T2>T3>T1 (c)T3>T2>T1 (d)T1>T3>T2

Identify the correct statement from the following

The logic circuit shown above is equivalent to:

What is acceleration of free tall

show that area under the velocity time graph of a body moving 1) uniformly and 2) with a constant acceleration is displacement

How to find formal charge of NO?

A man wants to cross the river to an exactly opposite point on the other bank. If he can row his boat with 2√3 times the velocity of the current, then at what angle to the current he must keep the boat pointed?

The wavelength of the first line in Balmer series in the hydrogen spectrum is λ. What is the wavelength of the second line?

What will be the depth of object 'O' for an observer just below the interface CD? (μ3>μ2>μ1)

A sphere of radius R has a uniform distribution of electric charge in its volume. At a distance x(<R) from its centre, the electric field is directly proportional to