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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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True or False- For resistors in series, the larger the resistance is, the larger the voltage drop that is required.​
WINSTONCH [101]

Answer:

I think its true

8 0
2 years ago
Read 2 more answers
A person's prescription for her new bifocal glasses calls for a refractive power of -0.450 diopters in the distance-vision part,
Angelina_Jolie [31]

Answer:

Far point of the eye is 22.24 m

Far point of the eye is 0.4 m

Explanation:

\frac{1}{f}=-0.045

Object distance = u

Image distance = v

Lens equation

\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\\\Rightarrow \frac{1}{f}-\frac{1}{u}=\frac{1}{v}\\\Rightarrow \frac{1}{v}=-0.045-\frac{1}{\infty}\\\Rightarrow \frac{1}{v}=\frac{1}{-0.045}\\\Rightarrow v=-22.22\ m

Far point

|v|+\text{Position from eye}\\ =|-22.22|+0.02\\ =22.24\ m

Far point of the eye is 22.24 m

Object distance = u = 0.25-0.02 = 0.23 m

\frac{1}{f}=1.75

\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\\\Rightarrow \frac{1}{f}-\frac{1}{u}=\frac{1}{v}\\\Rightarrow \frac{1}{v}=1.75-\frac{1}{0.23}\\\Rightarrow v=-0.38\ m

Near point

|v|+\text{Position from eye}\\= |-0.38|+0.02\\ =0.4\ m

Far point of the eye is 0.4 m

7 0
3 years ago
ΔP = 1.88 x 10^4 Pa. Use this answer to estimate the volume flow rate of blood from the head to the feet of a six-foot-tall pers
Sveta_85 [38]

Answer: 3765.66 \frac{m^{3}}{s}

Explanation:

We can solve this problem using the <u>Poiseuille equation</u>:

Q=\frac{\pi r^{4}\Delta P}{8\eta L}

Where:

Q  is the Volume flow rate

r=23 cm \frac{1 m}{100 cm}=0.23 m  is the effective radius

L=6 ft \frac{0.3048 m}{1 ft}=1.8288 m  is the length

\Delta P=1.88(10)^{4} Pa  is the difference in pressure

\eta=3(10)^{-3} Pa.s is the viscosity of blood

Solving:

Q=\frac{\pi (0.23 m)^{4}(1.88(10)^{4} Pa)}{8(3(10)^{-3} Pa.s)(1.8288 m)}

Q=3765.66 \frac{m^{3}}{s}

7 0
3 years ago
Blocks A (mass 3.50 kg) and B (mass 6.50 kg) move on a frictionless, horizontal surface. Initially, block B is at rest and block
Vedmedyk [2.9K]

Answer:

(a) V (A) =  0.7 m/s,

(b) V (A) =  0.7 m/s,

(c) V (B) =  0.7 m/s

(d) u= - 0.60 m/s

(e) v = 0.75 m/s

Explanation:

Given:

M(A) =3.50 Kg, M(B)=6.50 Kg, V(A) = 2.00 m/s, V(B) = 0 m/s

Sol:

a)  law of conservation of momentum

M(a) x V(A) + M(B) x V(B) = ( M(a) + M(B) ) V      (let V is Common Velocity of Both block)

so 3.50 Kg x 2.00 m/s + 6.50 Kg x 0 m/s = (3.50 Kg + 6.50 Kg ) V

after solving V =  0.7 m/s

After the collision the velocities of the both block will be as the the spring is compressed maximum.

V (A) =  0.7 m/s

b)  V(A) =  0.7 m/s ( Part (a) and Part (a) are repeated )

c) as stated above the in the Part (a)

V(B) =  0.7 m/s

d) When the both blocks moved apart after the collision:

Let u=velocity of block A after the collision.

and v = velocity of block B after the collision.

then conservation of momentum

M(a) x V(A) + M(B) x V(B) = M(a) x v + M(B) x u

⇒ 3.50 Kg x 2.00 m/s + 6.50 Kg x 0 m/s =  3.50 Kg x u + 6.50 Kg x v

⇒ 2.00 m/s = u + 1.86 v -----eqn (1)  ( dividing both side by 3.50 Kg)

For elastic collision  

the velocity relative approach = velocity relative separation

so 2.00 m/s = v-u  ----- eqn (2)

⇒v = u + 2.00 m/s

putting this value in eqn (1) we get

2.00 m/s = u + 1.86 (v + 2.00 m/s)

u= - 0.60 m/s

e) putting v= 2.00 m/s in eqn (1)

2.00 m/s = - 2.32 m/s + 1.86 v

v = 0.75 m/s

5 0
3 years ago
If the car’s speed decreases at a constant rate from 71 mi/h to 50 mi/h in 3.0 s, what is the magnitude of its acceleration, ass
melisa1 [442]

Answer:

The acceleration and the distance are 25200 mi/h² and 0.1008 mi.

Explanation:

Given that,

Initial speed = 71 mi/h

Final speed = 50 mi/h

Time = 3.0 s

(a). We need to calculate the acceleration

Using equation of motion

v=u+at

a=\dfrac{v-u}{t}

Put the value in the equation

a=\dfrac{(50-71)\times3600}{3}

a=-25200\ mi/h^2

Negative sign shows the deceleration.

(b). We need to calculate the distance

Using equation of motion

v^2=u^2+2as

(50)^2=(71)^2+2\times(-25200)\times s

s=\dfrac{(50)^2-(71)^2}{-25200}

s=0.1008\ mi

Hence, The acceleration and the distance are 25200 mi/h² and 0.1008 mi.

8 0
3 years ago
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