1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
JulijaS [17]
3 years ago
14

The phase velocity of transverse waves in a crystal of atomic separation a is given byy = csin(ka/2) pka/2 1. What is the disper

sion relation e(k)? 2. What is the group velocity as a function of k?
Physics
1 answer:
damaskus [11]3 years ago
7 0

Answer:

a

e(k) =  \frac{2a}{c}  *  sin (\frac{k*a}{2} )

b

G_{v} =  \frac{d e(k ) }{dk }  =  \frac{a^2}{c}  *  cos (\frac{k* a}{2} )

Explanation:

From the question we are told that

    The  velocity  of transverse waves in a crystal of atomic separation is  

                  b_y  = c \frac{sin (\frac{k*a}{2} )}{\frac{k*a}{2} }

Generally the dispersion relation is mathematically represented as

            e(k) =  b_y  *  k

=>    e(k) = c  \frac{sin(\frac{k*a}{2} ) }{ \frac{k*a}{2} }  *  k

=>    e(k) =   c *  \frac{sin (\frac{k_a}{2} )}{ \frac{a}{2} }

=>    e(k) =  \frac{2a}{c}  *  sin (\frac{k*a}{2} )

Generally the group velocity is mathematically represented as

          G_{v} =  \frac{d e(k ) }{dk }  =  \frac{a^2}{c}  *  cos (\frac{k* a}{2} )

You might be interested in
is plugged into the outlet of a 120−V circuit that has a 20−A circuit breaker. You plug an electric hair dryer into the same out
WINSTONCH [101]

Answer:

Given the point of maximun electric power of the hair dryer 1500 (w); The circuit breaker won´t trip at all

Explanation:

The most simplyfied  relation between power, voltage and current is:

Electric power (in watts) =Voltage (in volts) * current (in ampers)

In the case of P= 1500 (w) and V= 120 (v) we have:

I = 1500/120 (a)    = 12,65 (a)

This value  is far away of 20 (a) (the nominal trip current

8 0
3 years ago
How far did a frog jump if he travels at a rate of 2.1 m/s for 10 seconds?
Anestetic [448]

Answer:

21 m

Explanation:

The motion of the frog is a uniform motion (constant speed), therefore we can find the distance travelled by using

d=vt

where

d is the distance covered

v is the speed

t is the time

The frog in this problem has a speed of

v = 2.1 m/s

and therefore, after t = 10 s, the distance it covered is

d=(2.1)(10)=21 m

3 0
3 years ago
A crate is placed on an adjustable, incline board. the coefficient of static friction between the crate and the board is 0.29.
sasho [114]

Let the angle be Θ (theta)

Let the mass of the crate be m.

a) When the crate just begins to slip. At that moment the net force will be equal to zero and the static friction will be at the maximum vale.

Normal force (N) = mg CosΘ

μ (coefficient of static friction) = 0.29

Static friction = μN = μmg CosΘ

Now, along the ramp, the equation of net force will be:

mg SinΘ - μmg CosΘ = 0

mg SinΘ = μmg CosΘ

tan Θ = μ

tan Θ = 0.29

Θ = 16.17°

b) Let the acceleration be a.

Coefficient of kinetic friction = μ = 0.26

Now, the equation of net force will be:

mg sinΘ - μ mg CosΘ = ma

a = g SinΘ - μg CosΘ

Plugging the values

a = 9.8 × 0.278 - 0.26 × 9.8 × 0.96

a = 2.7244 - 2.44608

a = 0.278 m/s^2

Hence, the acceleration is 0.278 m/s^2

7 0
3 years ago
Please help and I don't mean to sound rude but, ONLY ANSWER IF YOUR GOING TO DO ALL 4 QUESTIONS
anzhelika [568]

Answer:

for first question is 2

for second question 1

for third question 2

for forth question 1

Explanation:

i hope i helped

6 0
3 years ago
A negative point charge - is at the center of a hollow insulating spherical shell, which has an inner radius R1 and an outer rad
Vaselesa [24]
The Explanation is Below

8 0
3 years ago
Other questions:
  • Charge is placed on two conducting spheres that are very far apart and connected by a long thin wire. The radius of the smaller
    7·1 answer
  • A picture shows the letter "O" made from a piece of plastic. Where is the center of gravity? USE THE DEFINITION OF THE CENTER OF
    10·1 answer
  • What are fossil fuels made of?
    13·1 answer
  • What did Rutherford discover about the structure of the atom
    15·1 answer
  • At a pressure of one billionth (10–9) of atmospheric pressure, there are about 2.7 × 1010 molecules in one cubic centimeter of a
    6·1 answer
  • Microwaves and infrared waves are similar because they both have
    11·2 answers
  • How does the gravitational force between two objects change if the mass of
    8·1 answer
  • (quick help please??)A mechanic uses a mechanical lift to raise a car. The car weighs 10,200 N. The work required to do this was
    14·1 answer
  • Find the moment of force of 60 Newton about an axis of rotation at distance 20 cm from the force​
    7·1 answer
  • A car drives 200 miles east then makes a turn and travels 50 miles north before
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!