Tagged Questions
1
vote
1answer
50 views
How large of a solar sail would be needed to travel to mars in under a year?
I'm attempting to approach this using the identity
$$F/A = I/c$$
I can solve for Area easily enough
$$A = F(c/I)$$
and I know the distance $d$ is
$$d=1/2(at^2)$$
But I'm having difficulty trying to ...
0
votes
1answer
54 views
The second resonance of string?
What is the relationship between "the second resonance " and string and the wavelength. Like in this question: if the length of the string is 2cm with second resonance, then what is wavelength?
0
votes
0answers
14 views
Minimum thickness of bubble ensuring max reflectance
A soap bubble has index of refraction of 1.33. What minimum thickness of this bubble will ensure max reflectance of normally incident 530 nm light?
Ans is 99.6, but how do I get that?
I am ...
2
votes
3answers
73 views
How to determine the direction of medium's displacement vectors of a standing wave?
Consider the following problem taken from a problem booklet. My questions are:
What is displacement vector?
And how to determine the direction of displacement vector at a certain point?
Where is the ...
1
vote
0answers
57 views
Double Slit Problem Involving Superposition of Wave Equation [closed]
Here's my question:
To be clear it's part (iv) that's unclear to me.
I can see that the important bit is that the exposure is over a LONG time. Hence, this must have some implication on the manner ...
-5
votes
0answers
53 views
Could anyone help me to interpret the wave geometrically? [closed]
This is the problem:
A 180-MHz wave travels in medium characterized by $\mu_r = 1$, $\epsilon_r = 25$, and $\sigma = 2.5$ mS/m. The electric field intensity is given by $\widetilde{E} = ...
1
vote
3answers
108 views
Waveguides (in the ocean?)
The speed of sound in the ocean is given by
$$c_s(\theta,z) = 1450 + 4.6\theta - 0.055\theta^2 + 0.016z$$
$\theta$ is the temperature in degrees celcius, and $z$ is the depth. In a simplified model, ...
0
votes
1answer
72 views
Standing Waves: finding the number of antinodes
A string with a fixed frequency vibrator at one end forms a standing wave with 4 antinodes when under tension T1. When the tension is slowly increased, the standing wave disappears until tension T2 is ...
0
votes
2answers
94 views
Calculating phase difference of sound waves
An observer stands 3 m from speaker A and 5 m from speaker B. Both speakers, oscillating in phase, produce waves with a frequency of 250 Hz. The speed of sound in air is 340 m/s. What is the phase ...
0
votes
0answers
84 views
Amplitude and frequency of a wave [closed]
What is the amplitude and frequency of the wave given by the equation:
$y = A \sin^2(kx - \omega t)$ ?
-3
votes
1answer
153 views
How to reconstruct information from a graph of an oscillation? [closed]
We are given a graph of the position of a wave (amplitude).
How can we calculate the wavelength, frequency and the maximum speed of a particle attached to that wave?
We have
Speed = wave length ...
0
votes
0answers
78 views
What will be the speed of the wave when the temperature is lowered by 14.3 Co? [closed]
A copper wire, whose cross-sectional area is 5.22 x 10-6 m2, has a linear density of 5.86 x 10-3 kg/m and is strung between two walls. At the ambient temperature, a transverse wave travels with a ...
0
votes
1answer
156 views
Transmission of Gaussian Beam Through Graded-Index Slab
The $ABCD$ matrix of a glass graded-index slab with refractive index $n(y)=n_0(1-\frac{1}{2}\alpha^{2}y^{2})$ and length $d$ is $A=\cos(\alpha d)$, $B=\frac{1}{\alpha}\sin(\alpha d)$, $C=-\alpha ...
1
vote
0answers
121 views
Help With Difficult Deductive Proof [closed]
Suppose we have a Gaussian beam with a complex envelope expressed by the following equation 1:
$$\tag{1}
A_G(x,y,z) = \frac{A_1}{q(z)} e^{-ik \frac{x^2 + y^2}{2q(z)}}
$$
where
$$
q(z) = z+iz_0
$$
...
0
votes
1answer
58 views
Percentage increase in the length of pendulum
I'm struggling with a physics question :
What should be the percentage increase in the length of the chord of a pendulum for the period increased by 1%?
The answer is 2%.
I tried with $w = 2 \pi/T ...
0
votes
1answer
267 views
How do we find the frequency of wave propagated along the x-axis?
I don't know how to solve question like this:
A transverse wave is propagated in a string stretched along the x-axis. The equation of the wave, in SI units, is given by:y = 0.006 cos π(46t - 12x). ...
2
votes
3answers
203 views
waves on water generated by a falling object
Let an object of mass $m$ and volume $v$ be dropped in water from height $h$, and $a$ be the amplitude of the wave generated. What is the relation between $a$ and $h$. How many waves are generated? ...
2
votes
2answers
364 views
Galilean transformation of wave equation
I have this general wave equation:
\begin{equation}
\dfrac{\partial^2 \psi}{\partial x^2}+\dfrac{\partial^2 \psi}{\partial y^2}-\dfrac{1}{c^2}\dfrac{\partial^2 \psi}{\partial t^2}=0
\end{equation}
...
0
votes
2answers
183 views
So where is mistake in the formula of wave number (magnitude of wave vector)?
I have following form for wave vector $k_2=n_2 \omega/c_0$. Now because $\omega=2 \pi c/ \lambda$, then $k_2=n_2 \omega/c_0=\frac{n_2 2 \pi c_0}{c_0 \lambda}=\frac{n_2 2 \pi}{\lambda}$. But problem is ...
0
votes
0answers
61 views
Can a wave propagate in an elastic fluid in the absence of volume forces?
A motion (wave) $\mathbf{x}: \mathcal{B}_0 \times [t_0,t_1] \to \mathcal{E}:$ such that
$q-o = \mathbf{x}(p,t)=(p-o)+\mathbf{a}_0 cos(\mathbf{k}_0\cdot(p-o) - \omega_0 t)$
can propagate in an elastic ...
2
votes
1answer
159 views
Confusion concerning the use of wavenumber in exercise about Fabry-Perot etalon
In the exercise we are given that the spectrum of a light source consists of two spectral lines, which both have wavelengths around $500 \text{ nm}$ and the separation between them - given in ...
2
votes
1answer
210 views
Counting the number of modes
The exercise is the following
Show that the number $N(\lambda) \, \mathrm d \lambda$ of standing electromagnetic waves (modes) in a large cube of volume $V$ with wavelengts within the interval ...
0
votes
1answer
481 views
Changing magnetic flux graph?
In regards to a graph of the changing magnetic flux in a generator such as this one:
a) The equation of the graph should be $\Phi = BA \cos \theta$. As $\theta=\omega t$ (angular velocity*time), ...
1
vote
0answers
341 views
Double Slit Problem, Waves and Optics [closed]
Given d(slit separation)= $0.158\:\rm{mm}$, $\lambda _{red}= 665\:\rm{nm}$, $\lambda _{g/y}= 565nm$, L(distance from screen)= $2.24\:\rm{m}$
What is the distance between the third order red and ...
0
votes
1answer
172 views
Standing Wave: How to show that $\frac{\mathrm df}{f}=0.5\frac{\mathrm dF}{F}$ where $f$ is frequency and $F$ is tension of the string?
How to do this?
Show that if the tension $F$ in a string is changed by a small amount $\mathrm dF$, the fractional change in frequency of a standing wave, $\frac{\mathrm df}{f}$ is given by:
...
