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
miss Akunina [59]
3 years ago
12

A photoelectric effect experiment finds a stopping potential of 1.93 V when light of wavelength 200 nm is used to illuminate the

cathode.
a.) what metal is the cathode made?
b.) what is the stopping potential if the intensity of light is doubled?
Physics
1 answer:
PSYCHO15rus [73]3 years ago
6 0

a) zinc

The equation of the photoelectric effect is:

E=\phi + K (1)

where

E is the energy of the incident light

\phi is the work function

K is the maximum kinetic energy of the emitted photoelectrons

Here the wavelength of the incident light is

\lambda=200 nm = 2\cdot 10^{-7} m

so the energy of the light is

E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{2\cdot 10^{-7} m}=9.95\cdot 10^{-19} J

Converting into electronvolts,

E=\frac{9.95\cdot 10^{-19}}{1.6\cdot 10^{-19} J/eV}=6.22 eV (2)

The stopping potential is the potential needed to stop the photoelectrons with maximum kinetic energy: so, the electrical potential energy corresponding to the stopping potential (V=1.93 V) must be equal to the maximum kinetic energy of the photoelectrons,

U=q V = K

and since the charge of the electron is

1 q = 1 e

We have

K=(1 e)(1.93 V)=1.93 eV (3)

Combining (1), (2) and (3), we find the work function of the material:

\phi = E-K=6.22 eV-1.93 eV=4.29 eV

So, the cathode is most likely made of zinc, which has a work function of 4.3 eV.

b) The stopping potential does not change

As we said in part A), the stopping potential is proportional to the maximum kinetic energy of the photoelectrons, K.

The intensity of light is proportional to the number of photons that hit the surface of the metal. However, the energy of these photons does not depend on the intensity, but only on the frequency of the light.

Therefore, the energy of the photons (E) does not change when the intensity of light is doubled. Also, the work function \phi does not change: this means that the maximum kinetic energy of the photoelectrons, K, does not change, and so the stopping potential remains the same.

You might be interested in
How this induced force can be increased? Write three ways.
Ludmilka [50]
Strength of induced current increased when strength of magnetic field increases. It will also increase when the number of turns are increased or if the speed of conductor increases
8 0
3 years ago
If an object has a kinetic energy of 30 j and mass of 34kg how fast is the object moving ?
cricket20 [7]

Ek = (m*V^2) / 2 where m is mass and V is speed, then we can take this equation and manipulate it a little to isolate the speed.

Ek = mv^2 / 2 — multiply both sides by 2

2Ek = mv^2 — divide both sides by m

2Ek / m = V^2 — switch sides

V^2 = 2Ek / m — plug in values

V^2 = 2*30J / 34kg

V^2 = 60J/34kg

V^2 = 1.76 m/s — sqrt of both sides

V = sqrt(1.76)

V = 1.32m/s (roughly)

3 0
3 years ago
Determina el volumen de 450 g de alcohol
Rufina [12.5K]

Luego de utilizar la fórmula del volumen de un líquido encontramos que si el acohol tiene 450 gramos entonces su volumen es de

La fórmula del volumen de la densidad de un líquido es la siguiente:

Densidad= Masa / Volumen

Volumen =Masa / Densidad

Es conocido que la densidad del alcohol es 789 kg/m³, y como sabemos por dato que tiene 450gr el siguiente paso es la sustitución:

Volumen=0.45/ 789

Volumen = 0,00057 m³    

6 0
2 years ago
What are two advantages of using renewable resources?
Pavel [41]
One advantage is that whatever resource it is, it will never run out and you wont have to worry about not having it. A second is that there is going to be enough for everyone to use however much they want without there having to be a limit on how much you use.
3 0
3 years ago
When two or more different capacitors are connected in series across a potential source, which of the following statement must b
vova2212 [387]

Answer:

C. Each capacitor carries the same amount of charge.

Explanation:

When two or more different capacitors are connected in series across a potential source, each capacitor carries the same amount of charge.

In a series connected capacitor, sane amount of charge flows through the capacitors while different potential difference is passed across them.

The capacitors have the same charge as the charge flowing out directly from the potential source called emf since the emf is the driving force of charge in a circuit.

6 0
3 years ago
Other questions:
  • A golf ball stays on the tee until the golf club hits it. Which of the following principles best describes why this occurs? Grou
    9·1 answer
  • A person drives an automobile with a mass of 450 kilograms at a velocity of 26 meters per second. The driver accelerates to a ve
    5·1 answer
  • A pickup truck is carrying a toolbox, but the rear gate of the truck is missing, so the box will slide out if it is set moving.
    11·1 answer
  • CO2 , NaCl , HCl can be classified as ?
    8·1 answer
  • One hazard of space travel is debris left by previous missions. there are several thousand objects orbiting earth that are large
    8·1 answer
  • If you use such a tank to fill 0.020 m3 foil balloons (which don't stretch, and so have an internal pressure that is very close
    7·1 answer
  • Is it true or false that Science is a rigorous process, but is not subject to intense scrutiny by others
    12·1 answer
  • An electron is confined to a linear region with a length of the same order as the diameter of an atom (about 100 pm). Calculate
    13·1 answer
  • How does science restore diversity to areas where human activity has interfered with the natural structure of a habit/ecosystem?
    6·1 answer
  • Which of the following statements is true for real gases?
    12·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!