Phy 156 - Quiz 10

Direction of the electric field points

From positive to negative charges(From high to low potential)

discrete spectrum

a spectrum of separate and distinct colors in which not all colors are present

continuous spectrum

the emission of a continuous range of frequencies of electromagnetic radiation

The wavelength is 270 nm. What is the energy changE

1240/270 = 4.59 eV

The potential is 2.8 eV. The wavelength is

1240/2.8 = 442.9 nm

How and why the function of a metal is related to the threshold frequency of light for the photoelectric effect

They are related since the threshold frequency multiplied by Planck's constant is the work function.

Why the V stop is the stopping potential, in terms of the conservation energy

Since no energy can be created or destroyed, this would mean that the kinetic energy is equal to the potential energy. The kinetic energy is found by subtracting the work function from the energy of the photon.

Using the photoelectric equation, given an equation for eV stop vs frequency graph, what is the work function

The work function is the magnitude of the y intercept

Using the photoelectric equation, given an equation for eV stop vs frequency graph, what is the threshold frequency

The threshold frequency is the x-intercept

Using the photoelectric equation, given an equation for eV stop vs frequency graph, what does the slope represent

The slope represents Planck's constant

V stop

The stopping potential of the photon

hf in the photoelectric equation

hf represents the energy of the photon

When the intensity increases, the photons

The photons are released at an increased rate.

When the intensity increases, the electrons

The photons are released at an increased rate.

When the intensity decreases, the electrons

The electrons are released at an decreased rate.

When the intensity decreases, the photons

The photons are released at an increased rate.

When the intensity changes, the speed of photons emitted

Doesn't change

When the intensity changes, the speed of electrons emitted

Doesn't change

Momentum

mass x velocity

mass= 9.11 x 10^-31 kg, speed: 2.70 x 10^6 m/s. The wavelength:

(6.63 x 10^-34 J x s)/((9.11 x 10^-31 kg)(2.70 x 10^6 m/s)) =0.27 nm

absorption spectrum

The range of a pigment's ability to absorb various wavelengths of light.

Emission spectrum

a spectrum of the electromagnetic radiation emitted by a source.

Ground state

The lowest energy state of an atom (n=1)

Excited state

A state in which an atom has higher potential energy than it has in its ground state(n > 1)

Electron energies are negative because

This is because they are attracted to the nucleus

How to find the energy required to ionize an electron, given an electron level diagram

Take the positive value of the eV at the level it is trying to leave

Ionize

To leave the energy level

How to create an absorption spectrum given an energy level diagram

Divide 1240 by each of the wavelengths, then make these values the potential difference between each energy level and n=2.

Predicting which photons will be observed on an emission spectrum

Any potential difference subtracted by excited states or the ground state and the excited state will be emitted

Predicting which photons will be observed on an absorption spectrum

Any potential difference between one of the excited states and one of the ground states

If an electron energy diagram points downward, it

is photon emission

If an electron diagram reaches ground state, it is

Photon absorption

If the potential of the first capacitor is zero and the second one has a negative potential, the V stop is

Positive

If the potential of the first capacitor is zero and the second one is the stopping voltage, how does the kinetic energy of the electrons at the cathode compare to the eV stop

They are equal

Using the photon model of light, how can the effect that changing intensity has on the photons and electrons?

Using the photon model of light, it can demonstrate that total energy does increase with intensity, but not for individual electrons. Also, individually, energy is only increased by changing the wavelength or frequency

Using observation and the experiment, how can the effect that changing intensity has on the photons and electrons?

The electrons and photons being emitted have a direct relationship with the changing intensity.Since the stopping potential doesn't increase, the intensity doesn't impact the stopping voltage or the speed, since the stopping potential and the kinetic energy have a direct relationship

When the wavelength of light increases, the energy

decreases

When the wavelength of light decreases, the energy

increases

When the wavelength of light increases, the interference pattern

increases

When the wavelength of light decreases, the wavelength

decreases