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slava [35]
3 years ago
6

The photoelectric work function of a metal is the minimum energy needed to eject an electron by irradiating the metal with light

. For calcium, this work function equals 4.34 × 10−19 J. What is the minimum frequency of light for the photoelectric effect in calcium?
Physics
1 answer:
Vlada [557]3 years ago
3 0

Answer:

Minimum required frequency is υmin = 654.9 x 10¹² Hz

Explanation:

The energy of a photon is given by the equation:

E = hυ

where,

E = energy of photon

h = Plank's Constant = 6.626 x 10⁻³⁴ J.s

υ = frequency

The minimum energy of photon, must be equal to the work function of Calcium.

Emin = ∅₀ = h(υmin)

υmin = ∅₀/h

where,

υmin = minimum frequency

∅₀ = work function = 4.34 x 10⁻¹⁹ J

Therefore,

υmin = 4.34 x 10⁻¹⁹ J/6.625 x 10⁻³⁴ J.s

<u>υmin = 654.9 x 10¹² Hz</u>

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What are two processes that transfer water into the atmosphere
Ira Lisetskai [31]
Water enters the atmosphere through evaporation, transpiration, excretion and sublimation: Transpiration is the loss of water from plant

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4 0
3 years ago
A thin layer of liquid methylene iodide (n = 1.756) is sandwiched between two flat, parallel plates of glass (n = 1.50). What mu
Harrizon [31]

Answer:

t = 96.1 nm

Explanation:

For strong reflection through liquid layer we know that the path difference between two reflected light rays must be integral multiple of wavelength

now we know that the path difference of two reflected light from thin liquid layer is given as

2\mu t - \frac{\lambda}{2} = N\lambda

here we know that

\mu = 1.756

t = thickness of layer

N = 0 (for minimum thickness of layer)

\lambda = 675 nm

now we have

2(1.756) t = \frac{675 nm}{2}

t = 96.1 nm

5 0
3 years ago
Solve -7= sqrt 2x-9​
Sauron [17]

Answer:

x = 2

Explanation:

if it was -7 = the square root of both 2x-9 together, it would be false.

if it was square root of just 2x in the equation, the answer is:

x = 2

°°°°°°°°°

-7 = √2x - 9

-√2x = -9 + 7

√-2x = -2

√2x = 2

2x = 4

x = 2

4 0
3 years ago
A plastic rod 1.3 m long is rubbed all over with wool, and acquires a charge of -3e-08 coulombs. we choose the center of the rod
Anestetic [448]
(a) The plastic rod has a length of L=1.3m. If we divide by 8, we get the length of each piece:
L/8=1.3m/8=0.1625 m

(b) The center of the rod is located at x=0. This means we have 4 pieces of the rod on the negative side of x-axis, and 4 pieces on the positive side. So, starting from x=0 and going towards positive direction, we have: piece 5, piece 6, piece 7 and piece 8. Each piece is 0.1625 m long. Therefore, the center of piece 5 is at 0.1625m/2=0.0812 m. And the center of piece 6 will be shifted by 0.1625m with respect to this:
c_6 = 0.0812m+0.1625m=0.2437 m

(c) The total charge is Q=-3 \cdot 10^{-8}C. To get the charge on each piece, we should divide this value by 8, the number of pieces:
Q/8=-3\cdot 10^{-8}C/8=-3.75\cdot 10^{-9}C

(d) We have to calculate the electric field at x=0.7 generated by piece 6. The charge on piece 6 is the value calculated at point (c):
q= -3.75\cdot 10^{-9}C
If we approximate piece 6 as a single  charge, the electric field is given by
E=k_e  \frac{q}{d^2}
where k_e=8.99\cdot 10^9Nm^2C^{-2} and d is the distance between the charge (center of piece 6, located at 0.2437m) and point a (located at x=0.7m). Therefore we have
E= 8.99\cdot 10^9 Nm^2C^{-2} \frac{-3.75\cdot 10^9 C}{(0.2437m-0.7m)^2} =-161.9 V/m
poiting towards the center of piece 6, since the charge is negative.

(e) missing details on this question.
5 0
3 years ago
A heat pump with a COP of 3.15 is used to heat an air-tight house. When running, the heat pump consumes 5 kW of power. If the te
Jet001 [13]

Answer: 1026s, 17.1m

Explanation:

Given

COP of heat pump = 3.15

Mass of air, m = 1500kg

Initial temperature, T1 = 7°C

Final temperature, T2 = 22°C

Power of the heat pump, W = 5kW

The amount of heat needed to increase temperature in the house,

Q = mcΔT

Q = 1500 * 0.718 * (22 - 7)

Q = 1077 * 15

Q = 16155

Rate at which heat is supplied to the house is

Q' = COP * W

Q' = 3.15 * 5

Q' = 15.75

Time required to raise the temperature is

Δt = Q/Q'

Δt = 16155 / 15.75

Δt = 1025.7 s

Δt ~ 1026 s

Δt ~ 17.1 min

5 0
3 years ago
Read 2 more answers
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