This 2007 IIT JEE physics subjective practice problem requires the student to find the end correction, or difference between the frequency of a tuning fork and the corresponding sound waves inside of a tube, given the contextual information. This type of problem has an answer between 0 and 9999, with six points awarded for a correct answer. No points are subtracted for an incorrect response, so all problems in the subjective category may be attempted without penalty.
Problem
In the experiment for the determination of the speed of sound in air using the resonance column method, the length of the air column that resonates in the fundamental mode with a tuning fork is 0.30 m. When this length is changed to 1.00 m, the same tuning fork resonates with the first overtone. What is the end correction (in cm) for the column?
Solution
In the resonance column method, the pipe has one end closed and one end open. Let Δl be the end correction. Remember that the first resonance is, theoretically, one quarter of a wavelength, with the distance between resonances at half of a wavelength.
Thus, for the fundamental mode: 0.30 m + Δl = λ/4
For the first overtone: 1.00 m + Δl = 3λ/4
⇒ 3(0.30 m + Δl) = 1.00 m + Δl
⇒ Δl = 0.05 m = 5 cm.
Bio: Alexis Bonari is a freelance writer and blog junkie. She often can be found blogging about general education issues as well as information on college scholarships. In her spare time, she enjoys square-foot gardening, swimming, and avoiding her laptop.
Photo: Public Domain
URL: http://upload.wikimedia.org/wikipedia/commons/3/35/Kundt_tube.png
Friday, 20 August 2010
IITJEE/AIEEE quick links
Hi all
It is the high time that you are all set to start preparing for IITJEE/AIEEE 2011. Hera are few important links that would help you making a plan to get through IITJEE/AIEEE 2011 examination. So visit these links make your own plan that suites well with your time and start studying for getting into these high profile institutes.
1.IITJEE Pattern Analysis for Physics
2.IITJEE study material
3.Free prepeartion (assignments along with solutions) for IITJEE physics
4.IITJEE Physics Syllabus
5.IITJEE Institutes Information
6.IITJEE Chemistry Syllabus
7.IITJEE Math Syllabus
8.IITJEE Books for Physics Syllabus
If you want anything or any topic related to physics to be posted in this blog please let me know you can mail me at mailmephysics12@rediffmail.com
It is the high time that you are all set to start preparing for IITJEE/AIEEE 2011. Hera are few important links that would help you making a plan to get through IITJEE/AIEEE 2011 examination. So visit these links make your own plan that suites well with your time and start studying for getting into these high profile institutes.
1.IITJEE Pattern Analysis for Physics
2.IITJEE study material
3.Free prepeartion (assignments along with solutions) for IITJEE physics
4.IITJEE Physics Syllabus
5.IITJEE Institutes Information
6.IITJEE Chemistry Syllabus
7.IITJEE Math Syllabus
8.IITJEE Books for Physics Syllabus
If you want anything or any topic related to physics to be posted in this blog please let me know you can mail me at mailmephysics12@rediffmail.com
Tuesday, 17 August 2010
Heating effect of current and thermoelectricity
1. Heating effect of current
-In previous chapter while discussing electric energy and power ,we learned that IΔV amount of energy is lost per second when a current I flows through a potential ΔV and this energy appears in the form of heat energy
-Due to the conversion of electric energy into heat energy the conductor becomes hot .This effect is known as Joule's Heating and this heating is thermodynamics irreversible.
Cause Behind Joule's Heating:-
-Explanation behind the Joule's heating is that when a potential difference ΔV is maintained between the ends of a conductor,the free electrons in the conductor are accelerated towards the higher potential end of the conductor
-In their way electrons frequently collided withe the positive ions of the conductor due to which their velocity decreased
-This the energy electrons gained on account of acceleration is transferred to the positive lattice ions or atoms and electrons then returns to their equilibrium distribution of velocities
Thus ,lattice ions receives energy randomly at the average rate of IΔV per unit time
-Ions spends this energy by vibrating about their mean positions resulting in rise in the temperature of the conductor
-This way Joule's heating nothing but the conversion of electrical energy into heat energy
2. Thermoelectricity
-We know that currents flows in a conductor whenever there is a electric potential difference betweens the ends of the conductor If there is a temperature difference between the ends of the conductor then thermal energy flows from hotter end to the colder ends
-Thermal energy flows may also be carries by the electrons in the conductor and hence resulting the presence of electric current
-At the hotter end of the conductor electrons have slightly higher kinetic energy and hence they move faster
-So there is net flow of current towards the end of the conductor with lower temperature.Thus an electric current exists in the conductor due to the difference in the temperature of two ends of the conductor
-This phenonmenon due to which electricity is produced when two ends of the conductor are kept at different temperature is known as thermoelectricty
For more visit Heating effects of current
-In previous chapter while discussing electric energy and power ,we learned that IΔV amount of energy is lost per second when a current I flows through a potential ΔV and this energy appears in the form of heat energy
-Due to the conversion of electric energy into heat energy the conductor becomes hot .This effect is known as Joule's Heating and this heating is thermodynamics irreversible.
Cause Behind Joule's Heating:-
-Explanation behind the Joule's heating is that when a potential difference ΔV is maintained between the ends of a conductor,the free electrons in the conductor are accelerated towards the higher potential end of the conductor
-In their way electrons frequently collided withe the positive ions of the conductor due to which their velocity decreased
-This the energy electrons gained on account of acceleration is transferred to the positive lattice ions or atoms and electrons then returns to their equilibrium distribution of velocities
Thus ,lattice ions receives energy randomly at the average rate of IΔV per unit time
-Ions spends this energy by vibrating about their mean positions resulting in rise in the temperature of the conductor
-This way Joule's heating nothing but the conversion of electrical energy into heat energy
2. Thermoelectricity
-We know that currents flows in a conductor whenever there is a electric potential difference betweens the ends of the conductor If there is a temperature difference between the ends of the conductor then thermal energy flows from hotter end to the colder ends
-Thermal energy flows may also be carries by the electrons in the conductor and hence resulting the presence of electric current
-At the hotter end of the conductor electrons have slightly higher kinetic energy and hence they move faster
-So there is net flow of current towards the end of the conductor with lower temperature.Thus an electric current exists in the conductor due to the difference in the temperature of two ends of the conductor
-This phenonmenon due to which electricity is produced when two ends of the conductor are kept at different temperature is known as thermoelectricty
For more visit Heating effects of current
Monday, 16 August 2010
Pseudo or Fictitious forces
Consider a particle P in stationary frame of refrance S in which no force is acting i.e., a=0. If any other frame of refrance S' is moving with acceleration a w.r.t. frame S, then an acceleration -a0 appears to be acting on the particle P w.r.t. S'. Therefore a force -ma0 seems to be acting on the particle P due to the accelerated motion of the frame S'. This force is known as Pseudo force or fictitious force. Therefore pseudo forces are the force which does not actually acts on the particle but seems so because of the accelerated motion of the refrance frames are. This accelerated frame of refrance S' is a non inertial frame of refrance . If due to force FR on the inertial frame of refrance , the particle seems to suffer an acceleration aR then by Newtonian mechanics FR=maR Therefore resultant force on particle in accelerated frame is
F=FR+Fa
ma=maR+(-mF0)
or,
a=aR-a0
where Fa is fictitious force. Direction of fictitious force is opposite to the accelerated motion of S' frame of refrance.
F=FR+Fa
ma=maR+(-mF0)
or,
a=aR-a0
where Fa is fictitious force. Direction of fictitious force is opposite to the accelerated motion of S' frame of refrance.
Law of conservation of linear Momentum
Law of conservation of momentum is one of the basic laws and is derived from Newton’s Laws of motion. This law always holds true even in the situations where Newton’s laws of motion fails to hold. This law states that in the absence of resultant external force acting on the system , the total linear momentum of the system always remains constant i.e.,
p=p1+p2+p3+……+pn
This is law of conservation of linear momentum for system of particles. For individual particles momentum may change but their total momentum remain unaltered in absence of external forces.
Now the law of momentum is fundamental and exact law of nature. No violation to it has ever been encountered.
For more visit our website
Saturday, 14 August 2010
Newton's first law of motion
Hi all
What comes to your mind when you think about Newton's first law of motion . Now a days it has become an obvious statement but it was not the case when the law has been formulated. Statement of Newton's first Law of motion is
" Every body continues to be in state of rest or uniform motion untill acted upon by a net external force."
Equilibrium of the bodies is the essence of the forst law of motion.
Why we have used the word net force it is because there might be more then one forces acting on the body and net force on the body is the vector sum of all the forces acting on the body. Newton's first law of motion only gives the qualitative defination of the force that is it tells us that force is only the influence behind the moving objects but it does not tell anything about what is required to keep objects moving when they are set to motion by the application of force. In out daily life we see that bodies set to motion eventualy came to rest for example book placed on a horizontal surface is pushed , it started to move and then come to rest. What does first law of motion has to explain about this effect. What would we have to do to keep the book moving ? Can first law of motion has anything to say about it. Think about it if you find any more point to discuss let me know I'll be happy to discuss
Physics Expert
For complete notes on Newton's Laws of motion visit Newton's Laws of motion
What comes to your mind when you think about Newton's first law of motion . Now a days it has become an obvious statement but it was not the case when the law has been formulated. Statement of Newton's first Law of motion is
" Every body continues to be in state of rest or uniform motion untill acted upon by a net external force."
Equilibrium of the bodies is the essence of the forst law of motion.
Why we have used the word net force it is because there might be more then one forces acting on the body and net force on the body is the vector sum of all the forces acting on the body. Newton's first law of motion only gives the qualitative defination of the force that is it tells us that force is only the influence behind the moving objects but it does not tell anything about what is required to keep objects moving when they are set to motion by the application of force. In out daily life we see that bodies set to motion eventualy came to rest for example book placed on a horizontal surface is pushed , it started to move and then come to rest. What does first law of motion has to explain about this effect. What would we have to do to keep the book moving ? Can first law of motion has anything to say about it. Think about it if you find any more point to discuss let me know I'll be happy to discuss
Physics Expert
For complete notes on Newton's Laws of motion visit Newton's Laws of motion
Sunday, 1 August 2010
Work , Energy and Power (Quick Recap)
1. Work done by a constant force = F.S=FS cosθ
2. Work done by a variable force = ∫F.dS
3. If force acting on the body is along the direction of displacement of the body then work done can be calculated by calculating the area enclosed between F-S curve and displacement axis.
4. Work done by conservative forces like gravitational and electrostatic forces does not depend on the path taken by the particle and only depends on the initial and final positions of the particles.
5. Work done by non conservative forces like frictional forces are path dependent.
6. Power is the rate of doing work.
Average power = ΔW/Δt
Instantaneous power = dW/dt = F.v
7. Slope of W vs t graph gives the power of the system and area between the P vs t curve and time axis gives work done by the system.
8. Kinetic energy = (1/2)mv2
9. Gravitational potential energy = mgh where m is the mass of the object, g is acceleration due to gravity and h is the hight of object above the referance level. PE of the object is positive when object is above the refrence level and negative when it is below the refrence level.
10. An object posess kinetic energy by virtue of its motion and it posess potential energy by virtue of its position.
11. Elastic energy of a spring is given by (1/2)kx2 where k is the elastic constant for the spring.
12. Work energy theorem states that
Wext=Kf-Ki=ΔK
13. Law of conservation of energy states that " Total energy of the system always remains constant provided no external work is being done and energy of the system is not being converted to other forms of energy". Hence Energy can never be created or destroyed it can only be converted from one form of energy to another.
For full notes on Work energy and power visit the link
2. Work done by a variable force = ∫F.dS
3. If force acting on the body is along the direction of displacement of the body then work done can be calculated by calculating the area enclosed between F-S curve and displacement axis.
4. Work done by conservative forces like gravitational and electrostatic forces does not depend on the path taken by the particle and only depends on the initial and final positions of the particles.
5. Work done by non conservative forces like frictional forces are path dependent.
6. Power is the rate of doing work.
Average power = ΔW/Δt
Instantaneous power = dW/dt = F.v
7. Slope of W vs t graph gives the power of the system and area between the P vs t curve and time axis gives work done by the system.
8. Kinetic energy = (1/2)mv2
9. Gravitational potential energy = mgh where m is the mass of the object, g is acceleration due to gravity and h is the hight of object above the referance level. PE of the object is positive when object is above the refrence level and negative when it is below the refrence level.
10. An object posess kinetic energy by virtue of its motion and it posess potential energy by virtue of its position.
11. Elastic energy of a spring is given by (1/2)kx2 where k is the elastic constant for the spring.
12. Work energy theorem states that
Wext=Kf-Ki=ΔK
13. Law of conservation of energy states that " Total energy of the system always remains constant provided no external work is being done and energy of the system is not being converted to other forms of energy". Hence Energy can never be created or destroyed it can only be converted from one form of energy to another.
For full notes on Work energy and power visit the link
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