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elena55 [62]
4 years ago
6

The minimum frequency of light needed to eject electrons from a metal is called the threshold frequency, ???? 0 ν0 . Find the mi

nimum energy needed to eject electrons from a metal with a threshold frequency of 4.23× 10 14 s1 . 4.23×1014 s−1.
Physics
1 answer:
Allisa [31]4 years ago
7 0

Answer:

<h2>E = 2.8028*10⁻¹⁹ Joules</h2>

Explanation:

The minimum energy needed to eject electrons from a metal with a threshold frequency fo is expressed as E = hfo

h = planck's constant

fo = threshold frequency

Given the threshold frequency fo = 4.23×10¹⁴ s⁻¹

h = 6.626× 10⁻³⁴ m² kg / s

Substituting this value into the formula to get the energy E

E = 4.23×10¹⁴ *  6.626 × 10⁻³⁴

E = 28.028*10¹⁴⁻³⁴

E = 28.028*10⁻²⁰

E = 2.8028*10⁻¹⁹ Joules

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When a point charge of q is placed on one corner of a square, an electric field strength of 2 N/C is observed at the center of t
bearhunter [10]

Answer:

Explanation:

Net electric field at the centre will be zero .

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3 0
3 years ago
An object is located 50 cm from a converging lens having a focal length of 15 cm. Which of the following is true regarding the i
crimeas [40]

Answer:

It is real, inverted, and smaller than the object.

Explanation:

Let's start by using the lens equation to find the location of the image:

\frac{1}{q}=\frac{1}{f}-\frac{1}{p}

where we have:

q = ? is the distance of the image from the lens

f = 15 cm is the focal length (positive for a converging lens)

p = 50 cm is the distance of the object from the lens

Solving the equation for q, we find

\frac{1}{q}=\frac{1}{15 cm}-\frac{1}{50 cm}=0.047 cm^{-1}

q=\frac{1}{0.047 cm^{-1}}=+21.3 cm

The sign of q is positive, so the image is real.

Now let's also write the magnification equation:

h_i = - h_o \frac{q}{p}

where  

h_i, h_o are the size of the image and of the object

By substituting p = 50 cm and q = 21.3 cm, we find

h_i = - h_o \frac{21.3 cm}{50 cm}=-0.43 h_o

So we notice that:

|h_i| < |h_o| : this means that the image is smaller than the object

h_i < 0 : this means that the image is inverted

so, the correct option is:

It is real, inverted, and smaller than the object.

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Which best describes the surface of a concave mirror? It is flat. It is textured. It curves outward. It curves inward.
Sonja [21]

The concave mirror is a spherical-shaped mirror that has an inner curved surface. Hence, option (4) is correct.

What is a concave mirror?

The concave mirrors are spherical-shaped mirrors that are painted on the outward surface. It is also known as the converging mirror, having the recessed inner reflecting surface.

  • The concave mirrors are generally used for the purpose to focus the light. For that, they might have a reflecting surface, curved inwards, and the reflection of light is limited to the single focal point.
  • The reflecting surface of the concave mirror has its vertex or midpoint lying farther away from the objects than the edges.

Thus, we can conclude that the surface of the concave mirror is curved inward. Hence, option (4) is correct.

Learn more about the concave mirror here:

brainly.com/question/13300307

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