# Questions tagged [homework-and-exercises]

Applies to questions of primarily educational value - not only questions that arise from actual homework assignments, but any question where it is preferable to guide the asker to the answer rather than giving it away outright. Please READ THE GUIDANCE IN META before asking homework-like questions.

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### Electrostatics Question For JEE [closed]

A Conducting Sphere Has Charge Q uniformly distributed over its surface.Let a Gaussian Surface of same radius but passing through the centre of the same sphere. The total flux linked with the Gaussian ...
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### Its a physics exam question, I and my friend don't understand the theory and mechanics behind it [closed]

Two spheres each of mass m are connected by string of length 2l, are kept on a smooth horizontal surface. A vertical force F is applied at the middle of the string. What is the max value of F for ...
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### A question regarding electric field and charges inside a conductor

In this figure there is a positive point charge in the cavity and it creates an electric field, this polarises the charges in the conductor and the negative charges move towards the cavity where the ...
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### Find interval between scucessive conjunctions

The maths here doesn't seem to be too hard, but for some reason I can't quite figure out what to do: Consider two planets orbiting a star in circular orbits with periods $T_1$ and $T_2$. What is the ...
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### Ladder Operators Calculate Inner Product

We have the step-down and step-up ladder operators, and I am trying to calculate $\langle\alpha|a^†aa^†|\alpha\rangle$, I know that $a|\alpha\rangle = \alpha|\alpha\rangle$ and $|\alpha\rangle$ is ...
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### Exercise 32 from Bernard Schutz

The exercise In Bernard Schutz's 'General Relativity, there is an exercise, I don't understand how to start with. To develop a TT Gauge, we should use the given transformation. But somehow I am ...
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### Finding a new hamiltonian from a given canonical transformation

Let us suppose we have a given Hamiltonian $$H = \frac{P_1^2}{4}+\frac{P_2^2}{2}+V(Q_2)$$ and $q_1 = Q_1 + Q_2/2$ with $q_2 = Q_1 - Q_2/2$. I need to find the new hamiltonian by using these canonical ...
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### Flux linked with coil [closed]

when a super conducting loop with zero resistance is moving towards a magnetic, the flux linked with the loop is a) Increases b) Decreases c) Remains constant d) First increases then decreases
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### Symmetrical, spherical charge distribution [closed]

I have this problem from my Electromagnetism class, but I don´t have a lot of idea in how to solve it. Show that for a symmetrical, spherical charge distribution $\rho(\vec{r})=\rho(r)$ (with $r$ ...
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### Net bound surface charge density of capacitor

Q. In a parallel plate capacitor, two dielectric slabs of thickness 5 cm each are inserted between the plates and a potential of 100 V is applied across it. The value of the net bound surface charge ...
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### How to (derivate and) apply the electric field formula? [closed]

this question might be straightforward but I'm getting lost and I feel like I wouldn't be able to proceed if I don't get this clear from the get-go. I get the basic idea behind finding the electric ...
49 views

### Finding equation for acceleration of a mass connected to a massless spring [closed]

If a mass of $5$ kg connected to one end of a spring is released from the elongated position and its corresponding angular velocity is governed by the equation $\omega =t^3+t^2+1$ then what is its ...
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### Hooke's law and modulus of elasticity [closed]

I'm having trouble in understanding the following question which state modulus of elasticity in Newton. Is it possible that we can define modulus of elasticity in Newton somehow?? I am getting a wrong ...
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### Konig's Theorems

In the proof of Konig's Theorems the following identity is used: $$\underline{v_i} = \underline{v_i'} + \underline{v_c}$$ which is the law of transformation of velocity when passing from the ...
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### Question about quantum scattering theory (elastic) [closed]

I tried to solve this question and reach to this: J1=ħ/m Im[ψ*(incident)dψ/dz]=ħk/m J2=ħ/m Im[ψ*(scattered)(gradient ψ)] =ħ/m Im[f*(θ) (e^-ikr)/r (d/dr +1/r d/dθ+1/rsinθ d/dφ) (f(θ) e^ikr)] =ħ/m Im[|...
1 vote
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### On reciprocal lattice properties

As a consequence of the translational invariance of an ideal crystal, it's reasonable to assume that this periodicity must be recognised in any function $f({\mathbf r})$ of physical interest for the ...
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1 vote
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### Proving a relationship involving the chemical potential [closed]

I need to prove the relation $$\left(\frac{\partial \mu}{\partial N}\right)_{T,V}> \left(\frac{\partial \mu}{\partial N}\right)_{T,P}.$$ One may start with the total differential of the internal ...
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### Maintaining the balance of a rod of uniform density

Assume a rod which: is of uniform density $\rho$. is a metre long. The rod is balanced on a knife edge at 58 cm. mark (in the notation where the extreme left side is assumed to be 0). To the extreme ...
• 207
28 views

### Extension in Massive Springs under gravity

Suppose we have a spring which has a uniform cross sectional area $A$, and has a uniform linear mass density $J$, and has a total unstretched length $L$. Let the spring also obey Hooke's Law. Further, ...
• 197
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### Intensity pattern in Double slit experiment [closed]

This question appeared in my yearly exams regarding the intensity distribution of bright fringes in YDSE . If the screen is brought closer to the plane of slits , does the intensity of bright fringes ...
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### Electric field strength [closed]

I have got a problem to solve which is quite a way out of my understanding and was looking for help: A thin, horizontal, straight rod evenly charged throughout the whole length, which is 2a, is in a ...
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### Boat River Problem (Relative motion) [closed]

On a river coast, there is a port; when a barge passed the port, a motor boat departed from the port to a village at the distance s1 = 15 km downstream. It reached its destination After 45 min, turned ...
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### Calculate the transition amplitude and the differential cross section [closed]

Calculate the transition amplitude and the differential cross section for the lowest order process in perturbation theory in which a photon strikes an electric charge core Ze and the heavy core ...
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### Collision of $\rm H$ atoms [closed]

The question is: Two $\rm H$ atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced by__________ well in this question I solved it ...