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Assoli18 [71]
3 years ago
6

Light of 1.5 ✕ 1015 hz illuminates a piece of tin, which has a work function of 4.97 ev. (a) what is the maximum kinetic energy

of the photoelectrons?
Physics
1 answer:
stiks02 [169]3 years ago
8 0
In the photoelectric effect, the energy of the incoming photon (E=hf) is used in part to extract the photoelectron from the metal (work function) and the rest is converted into kinetic energy of the photoelectron:
hf = \phi + K
where
h is the Planck constant
f is the frequency of the incident light
\phi is the work function of the material
K is the kinetic energy of the photoelectron.

The photoelectron generally loses part of its kinetic energy inside the material; however, we are interested in its maximum kinetic energy, that is the one the electron has when it doesn't lose energy, so we can rewrite the previous equation as
K_{max} = hf - \phi

The work function is (in Joule)
\phi = (4.97 eV)(1.6 \cdot 10^{-19} J/eV)=7.95 \cdot 10^{-19} J

and using the data of the problem, we find the maximum kinetic energy of the photoelectrons
K_{max} = (6.6 \cdot 10^{-34} Js)(1.5 \cdot 10^{15} Hz)-7.95 \cdot 10^{-19}J= 1.95 \cdot 10^{-19} J

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charle [14.2K]
Definition formula for momentum: P = mv

So P(A) = 0.45 * 50 = 22.5 kgm/s

P(B) = 0.45 * 80 = 36 kgm/s

P(C) = 0.45 * 25 = 11.25 kgm/s

B has the greatest momentum
4 0
3 years ago
Read 2 more answers
Two cylindrical resistors are made from the same material. The shorter one has length L, diameter D, and resistance R1. The long
nordsb [41]

Answer:

the resistance of the longer one is twice as big as the resistance of the shorter one.

Explanation:

Given that :

For the shorter cylindrical resistor

Length = L

Diameter = D

Resistance = R1

For the longer cylindrical resistor

Length = 8L

Diameter = 4D

Resistance = R2

So;

We all know that the resistance of a given material can be determined by using the formula :

R = \dfrac{\rho L }{A}

where;

A = πr²

R = \dfrac{\rho L }{\pi r ^2}

For the shorter cylindrical resistor ; we have:

R = \dfrac{\rho L }{\pi r ^2}

since 2 r = D

R = \dfrac{\rho L }{\pi (\frac{2}{2 \ r}) ^2}

R = \dfrac{ 4 \rho L }{\pi \ D   ^2}

For the longer cylindrical resistor ; we have:

R = \dfrac{\rho L }{\pi r ^2}

since 2 r = D

R = \dfrac{ \rho (8 ) L }{\pi (\frac{2}{2 \ r}) ^2}

R = \dfrac{32\rho L }{\pi \ (4 D)   ^2}

R = \dfrac{2\rho L }{\pi \ (D)   ^2}

Sp;we can equate the shorter cylindrical resistor to the longer cylindrical resistor as shown below :

\dfrac{R_s}{R_L} = \dfrac{ \dfrac{ 4 \rho L }{\pi \ D   ^2}}{ \dfrac{2\rho L }{\pi \ (D)   ^2}}

\dfrac{R_s}{R_L} ={ \dfrac{ 4 \rho L }{\pi \ D   ^2}}* { \dfrac  {\pi \ (D)   ^2} {2\rho L}}

\dfrac{R_s}{R_L} =2

{R_s}=2{R_L}

Thus; the resistance of the longer one is twice as big as the resistance of the shorter one.

7 0
3 years ago
A 4.0kg block is sliding with a constant velocity of 3.0m/s on a frictionless table that is 0.5m high. If all of the block’s ene
MArishka [77]

Answer:

Velocity = 4.33[m/s]

Explanation:

The total energy or mechanical energy is the sum of the potential energy plus the kinetic energy, as it is known the velocity and the height, we can determine the total energy.

E_{M}=E_{p}  + E_{k} \\E_{p} = potential energy [J]\\E_{k} = kinetic energy [J]\\where:\\E_{p} =m*g*h\\E_{p} = 4*9.81*0.5=19.62[J]\\E_{k}=\frac{1}{2} *m*v^{2}  \\E_{k}=\frac{1}{2} *4*(3)^{2} \\E_{k}=18[J]\\Therefore\\E_{M} =18+19.62\\E_{M}=37.62[J]

All this energy will become kinetic energy and we can find the velocity.

37.62=\frac{1}{2} *m*v^{2} \\v=\sqrt{\frac{37.62*2}{4} } \\v=4.33[m/s]

8 0
3 years ago
Consider the following possibilities and select the correct choice.
dezoksy [38]

Answer:

Tx not but mybe

Explanation:

for that reason its just trying to help

4 0
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The ocean's level is currently rising at about
chubhunter [2.5K]

Answer:

The sea level will be 5m higher in 1667 y (years)

Explanation:

From the question, the rate at which the ocean's level is currently rising is about 3mm per year.

First, we will convert mm (millimeter) to m (meter)

1 mm = 0.001 m

Then,

3 mm = 3 × 0.001 m

= 0.003m

That is, the rate at which the ocean's level is currently rising is about 0.003m per year.

Now, to determine how long it will take for the ocean's level be 5 m higher than now at the given rate,

If the ocean rises 0.003 m in 1 year, then

the ocean will rise 5 m in x years

x = (5 m × 1 year) / 0.003 m

x = 5 / 0.003

x = 1666.67 years

x ≅ 1667 years

Hence, the sea level will be 5m higher in 1667 y (years)

8 0
3 years ago
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