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o-na [289]
3 years ago
11

Light of a single frequency falls on a photo-electric material but no electrons are emitted . Electrons may be emitted if the __

___________

Physics
1 answer:
lesya692 [45]3 years ago
8 0
Correct answer is "frequency of the light is increased".

The light that hits the photo-electric material consists of several photons, each one carrying an energy of
E=hf
where h is the Planck constant while f is the light frequency. Part of this energy is used to extract the photo-electrons from the material, and part it is converted into kinetic energy K of the electron:
hf= \phi + K
where \phi is the work function of the material, which is the amount of energy needed to extract the photo-electron.

If no photo-electrons are emitted, it means that the energy given by the photon is not enough to extract the photo-electron. But we see that the energy of the photon is directly proportional to the frequency of the light f, so in order to increase the energy, we should increase the frequency of the light.
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TRUE/FALSE, the scientific question is written like “I wonder if [dependent variable] is affected by [independent variable].”
sergiy2304 [10]
True as the independent variable is over the dependent variable and controls it as the dependent relies on the independent.
6 0
3 years ago
When the burner in a hot air balloon is turned on, the temperature of the air in the balloon ________ causing its volume to ____
Georgia [21]

<u>Answer</u>

Part 1) Increase

Part 2) expand

Part 3) rise


<u>Explanation</u>

When the air is heated the molecules gain kinetic energy and starts to collide with walls of the ballon making it to increase it size.

Thus the volume of the balloon expands. When this happens the balloon and its content becomes less dense and it rises.

5 0
3 years ago
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Which of the following statements is true?
erastova [34]

Hi there!

Question - Which of the following statements is true?

Answer - C. You are exposed to nuclear radiation every day.

Why - "radiation in the form of elementary particles emitted by an atomic nucleus, as alpha rays or gamma rays, produced by decay of radioactive substances or by nuclear fission."

6 0
3 years ago
A ball is thrown downward with an initial speed of 7 m / s. The ball's velocity after 3 seconds is m / s. (g = -9.8m / s²)
yan [13]

Answer:

-36.4 m/s

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5 0
3 years ago
A rock is being twirled in a circle on the end of a string. The string provides the centripetal force needed to keep the ball mo
KonstantinChe [14]

Answer:

No

Explanation:

The force of tension exerted by the string on the rock acts as centripetal force, so its direction is always towards the centre of the circle.

However, the direction of motion of the rock is always tangential to the circle: this means that the force is always perpendicular to the direction of motion of the rock.

As we know, the work done by a force on an object is

W=Fd cos \theta

where

F is the magnitude of the force

d is the displacement of the object

\theta is the angle between the force and the displacement

In this situation, F and d are perpendicular, so \theta=90^{\circ}, therefore cos \theta = 0 and the work done is zero:

W=0

4 0
2 years ago
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