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
Angelina_Jolie [31]
3 years ago
9

Photoelectric effect:

Physics
1 answer:
Lynna [10]3 years ago
5 0

Answer:

A. K = 0.546 eV

B. cooper and iron will not emit electrons

Explanation:

A. This is a problem about photoelectric effect. Then you have the following equation:

K=h\nu-\Phi=h\frac{c}{\lambda} -\Phi   (1)

K: kinetic energy of the ejected electron

Ф: Work function of the metal = 2.48eV

h: Planck constant = 4.136*10^{-15} eV.s

λ: wavelength of light = 410nm - 750nm

c: speed of light = 3*10^8 m/s

As you can see in the equation (1), higher the wavelength, lower the kinetic energy. Then, the maximum kinetic energy is obtained with the lower wavelength (410nm). Thus, you replace the values of all variables :

K=(4.136*10^{-15}eV)\frac{3*10^8m/s}{410*10^{-9}m}-2.48eV\\\\K=0.546eV

B. First you calculate the energy of the photon with wavelengths of 410nm and 750nm

E_1=(4.136*10^{-15}eV)\frac{3*10^{8}m/s}{410*10^{-9}m}=3.02eV\\\\E_2=(4.13610^{-15}eV)\frac{3*10^{8}m/s}{750*10^{-9}m}=1.6544eV

You compare the energies E1 and E2 with the work functions of the metals and you can conclude:

sodium = 2.3eV < E1

cesium = 2.1 eV < E1

cooper = 4.7eV > E1 (this metal will not emit electrons)

iron = 4.5eV > E1 (this metal will not emit electrons)

You might be interested in
What is the wavelength of a wave that has a speed of 350 meters/second and a frequency of 140 hertz?
sergey [27]

Answer:2.5m

Explanation:

3 0
2 years ago
If an electric current of 8.50 A flows for 3.75 hours through an electrolytic cell containing copper-sulfate (CuSO4) solution, t
muminat

Answer:

75.5g

Explanation:

From the ionic equation, we can write

CU^{2+}+SO^{2-}_{4}\\

next we find the number of charge

Note Q=it

for i=8.5A, t=3.75 to secs 3.75*60*60=13500secs

hence

Q=8.5*13500\\Q=114750C

Since one faraday represent one mole of electron which equal 96500C

Hence the number of mole produced by 114750C is

114750/96500=1.2mol

The mass of copper produced is

mol=\frac{mass}{molar mass} \\mass=mole*molar mass\\mass=1.2*63.5\\mass=75.5g

Hence the amount of copper produced is 75.5g

7 0
3 years ago
Read 2 more answers
When grocery shopping, the mass of the cart changes as you start to fill up your cart. How does the change in mass of your cart
Tasya [4]

Answer:

b

Explanation:

4 0
3 years ago
A dentist causes the bit of a high-speed drill to accelerate from an angular speed of 1.10 104 rad/s to an angular speed of 3.14
Anestetic [448]

Answer:

3.63 s

Explanation:

We can solve the problem by using the equivalent SUVAT equations for the angular motion.

To find the angular acceleration, we can use the following equation:

\omega_f^2 - \omega_i ^2 =2 \alpha \theta

where

\omega_f = 3.14\cdot 10^4 rad/s is the final angular speed

\omega_i = 1.10 \cdot 10^4 rad/s is the initial angular speed

\theta= 2.00 \cdot 10^4 rad is the angular distance covered

\alpha is the angular acceleration

Re-arranging the formula, we can find \alpha:

\alpha=\frac{\omega_f^2-\omega_i^2}{2\theta}=\frac{(3.14\cdot 10^4 rad/s)^2-(1.10\cdot 10^4 rad/s)^2}{2(2.00\cdot 10^4 rad)}=2.16\cdot 10^4 rad/s^2

Now we want to know the time the bit takes starting from rest to reach a speed of \omega_f=7.85\cdot 10^4 rad/s. So, we can use the following equation:

\alpha = \frac{\omega_f-\omega_i}{t}

where:

\alpha=2.16\cdot 10^4 rad/s^2 is the angular acceleration

\omega_f = 7.85\cdot 10^4 rad/s is the final speed

\omega_i = 0 is the initial speed

t is the time

Re-arranging the equation, we can find the time:

t=\frac{\omega_f-\omega_i}{\alpha}=\frac{7.85\cdot 10^4 rad/s-0}{2.16\cdot 10^4 rad/s^2}=3.63 s

4 0
3 years ago
Read 2 more answers
A certain spring stores 10.0J of potential energy when it isstretched by 2.00cm from its equilibrium position.How much potential
qaws [65]

Answer:

Answered

Explanation:

x= 0.02 m

E_p= 10.0 J

E_p= 0.5kx^2

10= 0.5k(0.02)^2

solving we get

K= 50.0 N/m

Now

E'_p= 0.5kx'^2

E'_p= 0.5×50×(0.04)^2

E'_p=40 J

b) potential energy is a scalar quantity and it only depends magnitude and not direction so it will remain same in compression and expansion both

c) 20 J = 0.5×50,000×x^2

solving

x= 0.028 m

d) k is 50.0 N/m  from above calculation

3 0
3 years ago
Other questions:
  • Volcanic eruptions are natural phenomena in the . They sometimes erupt, spilling out lava and dust. The lava solidifies, forming
    7·1 answer
  • If you have a 100-watt light bulb, how much energy does it use each minute?
    8·1 answer
  • A car travels 2 hours at 45 miles/ hour. How far did it go?
    13·1 answer
  • Sound waves need a ___________ for the vibrations to travel and they move in the pattern of a ______________ wave.
    7·1 answer
  • A fisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surfac
    7·1 answer
  • How much time passes when an object travels at a constant speed of 17 m/s over a distance of 323 m? Identify Variables, write fo
    13·1 answer
  • The Sl temperature scale used in science is the
    6·2 answers
  • Will Give Brainliest and 25 Points
    14·1 answer
  • A motorcycle traveling at 15 m/s accelerates at a constant rate of 4.0 m/s over a distance of 50 meters. What is the final veloc
    8·1 answer
  • A free undamped spring/mass system oscillates with a period of 4 seconds. When 10 pounds are removed from the spring, the system
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!