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Anni [7]
3 years ago
14

The following table lists the work functions of a few commonmetals, measured in electron volts.

Physics
1 answer:
steposvetlana [31]3 years ago
3 0

Answer:

Lithium

Explanation:

The equation for the photoelectric effect is

\frac{hc}{\lambda}= \phi + K_{max}

where

\frac{hc}{\lambda} is the energy of the incident photon, with

h being the Planck constant

c is the speed of light

\lambda is the wavelength of the photon

\phi is the work function of the metal (the minimum energy needed to extract the photoelectron from the metal)

K_{max} is the maximum kinetic energy of the emitted photoelectrons

In this problem, we have

\lambda= 190 nm = 1.9\cdot 10^{-7}m is the wavelength of the incident photon

K_{max}=4.0 eV is the maximum kinetic energy of the electrons

First of all we can find the energy of the incident photon

E=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{1.90\cdot 10^{-7} m}=1.05\cdot 10^{-18} J

Converting into electronvolts,

E=\frac{1.05\cdot 10^{-18} J}{1.6\cdot 10^{-19} J/eV}=6.6 eV

So now we can re-arrange the equation of the photoelectric effect to find the work function of the metal

\phi = E-K_{max}=6.6 eV - 4.0 eV=2.6 eV

So the metal is most likely Lithium, which has a work function of 2.5 eV.

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pantera1 [17]

Answer:

A. The closest point in the Moon's orbit to Earth

Explanation:

The perigee is defined as the closest point in the orbit of an object (such as a satellite) from the centre of the Earth. In this case, the Earth's satellite is the Moon, so the perigee is defined as the closest point in the Moon's orbit to Earth. so option A is the correct one.

Let's see instead the names of the other options:

B. The farthest point in the Moon's orbit to Earth  --> this point is called apogee

C. The closest point in Earth's orbit of the Sun  --> this point is called perihelion

D. The Sun's orbit that is closest to the Moon --> this point has no specific name

8 0
3 years ago
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How much work is done if a 15 newton suitcase is lifted 2 m ?​
nirvana33 [79]

Answer:

196 J

Explanation:

3 0
3 years ago
The area of the united states that has the highest level of average daily solar radiation by month would be
Vlada [557]
The area of the United States that has the highest level of Average Daily Solar radiation by month would be:

A) the Gulf Coast.
B) the Great Lakes.
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7 0
3 years ago
A car travels around a level, circular track that is 750m across. What coefficient of friction is required to ensure the car can
Crank

The coefficient of friction must be 0.196

Explanation:

For a car moving on a circular track, the frictional force provides the centripetal force needed to keep the car in circular motion. Therefore, we can write:

\mu mg = m\frac{v^2}{r}

where the term on the left is the frictional force acting between the tires of the car and the road, while the term on the right is the centripetal force. The various terms are:

\mu is the coefficient of friction between the tires and the road

m is the mass of the car

g=9.8 m/s^2 is the acceleration of gravity

v is the speed of the car

r is the radius of the curve

In this problem,

r = 750 m is the radius

v=85 mph \cdot \frac{1609}{3600}=38.0 m/s is the speed

And solving for \mu, we find the coefficient of friction required to keep the car in circular motion:

\mu = \frac{v^2}{rg}=\frac{38.0^2}{(750)(9.8)}=0.196

Learn more about circular motion:

brainly.com/question/2562955  

brainly.com/question/6372960  

#LearnwithBrainly

8 0
3 years ago
Suppose a runner completes one lap around a 400-m track in a time of 50 s. Calculate the average speed of the runner.
suter [353]

Answer:

8m/s

Explanation:

Average Speed = distance / time = 400/50 = 8m/s

6 0
3 years ago
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