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3 years ago

List four conditions that may result in the emission of electrons from a conductor

Physics

2 answers:

QveST [7]3 years ago

8 0

There are 4 ways in which electrons are emitted from the conductor.

i. Thermionic emission

ii. Electric field electron emission

iii. Photoelectric emission

iv. Secondary emission

In thermionic emission large amount of external energy in the form of heat is supplied to release free electrons from the metal.

In electric field electron emission, electrons are emitted from the metal surface when the metals are placed in a very strong electric field.

During photoelectric emission, light is absorbed by the metals and this provides energy to the valence electrons which break their bond with the parent atom and which are then released from the atom.

Valence electrons do have some kinetic energy, but they don't have enough energy to escape from the atom. During secondary emission, a high-speed electron is bombarded with an atom, which provides the energy for the valence electrons to break their bonds with their parent atom which are then released from the atom.

NNADVOKAT [17]3 years ago

3 0

Answer:

Conditions that result in the emission of electrons from a conductor:

Heating the conductor to a suitable temperature

Exposing the conductor to a strong light

Subjecting the conductor to a very high applied voltage

Subjecting the conductor to high-speed electrons from another source

Explanation:

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A circular test track for cars has a circumference of 4.7 km. A car travels around the track from the southernmost point to the

Alika [10]

Well, for the distance traveled, the car goes from the northernmost point to the southernmost point. So, it travels half of the circle's circumference = 4.7/2 = 2.35 km.

For the displacement, by going from the northernmost point to the southernmost point, the car basically just travels the diameter of circle.

So, using the formula: Circumference = 2πr = <span>πd

Hence, the d = C/</span>π = 4.7/<span>π = 1.49605... = 1.5 km (2 significant figures)
Therefore, displacement = 1.5 km</span>

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3 years ago

A small rock is thrown vertically upward with a speed of 27.0 m/s from the edge of the roof of a 21.0-m-tall building. The rock

lbvjy [14]

Answer:

A. 33.77 m/s

B. 6.20 s

Explanation:

Frame of reference:

Gravity g=-9.8 m/s^2; Initial position (roof) y=0; Final Position street y= -21 m

Initial velocity upwards v= 27 m/s

Part A. Using kinematics expression for velocities and distance:

$V_{final}^{2}=V_{initial}^{2}+2g(y_{final}-y_{initial})\\V_{f}^{2}=27^{2}-2*9.8(-21-0)=33.77 m/s$

Part B. Using Kinematics expression for distance, time and initial velocity

$y_{final}=y_{initial}+V_{initial}t+\frac{1}{2} g*t^{2}\\==> -0.5*9.8t^{2}+27t+21=0\\==> t_1 =-0.69 s\\t_2=6.20 s$

Since it is a second order equation for time, we solved it with a calculator. We pick the positive solution.

8 0

3 years ago

Would an increase in pressure favor the formation of ozone or of oxygen?

max2010maxim [7]

<h3><u>Answer;</u></h3>

<u>An increase in pressure favors the formation of ozone </u>

<h3><u>Explanation;</u></h3>

Ozone, O3, decomposes to molecular oxygen in the stratosphere according to the reaction

2O3(g) ⇆ 3O2 (g).

There are more moles of product gas than moles of reactant gas. An increase in total pressure increases the partial pressure of each gas, shifting the equilibrium towards the reactants.
Therefore; an increase in pressure favors backward reactions towards the formation of ozone.

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3 years ago

The amount or quality of light that is reflected from a mineral surface is known as __________. The amount or quality of light t

Eddi Din [679]

Answer:

C. Luster

Explanation:

Luster is a phenomenon which refers to the manner with which the outer surface of a mineral reflects light.

Depending on the mineral, the 'luster' can differ. For example, in some minerals, the surface appears to be translucent, while in others, the surface appears to be transparent.

There are different types of luster, but they are categorized majorly into two:

- Metallic luster (the surface of the mineral appears like the surface of a metal).

- Non metallic luster.

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3 years ago

When bridges are built, special joints must be used because the material of the bridge shrinks, and without these joints, the ma

egoroff_w [7]

Answer:

Option D.

Explanation:

The correct answer is Option D.

The shrinkage of the bridge material is because of thermal contraction.

Thermal contraction and thermal expansion are the phenomena of the bridge material which takes place due to the change in temperature of the atmosphere.

When the temperature of the surrounding increases expansion of the bridge material takes place and when temperature decreases the contraction of the material takes place.

This phenomenon sometimes damages the structure because due to continuous expansion and contraction of materials strength of the bridge decreases.

8 0

4 years ago