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KS4 Energy - Particles and Energy

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Particles

What happens to the kinetic energy of the particles when a gas is heated?

The heat energy is transferred to the kinetic energy of the gas particles.

What sort of graph would you get if you plotted ‘Kelvin temperature (Tk)’ against ‘the average kinetic energy (KEave)of the particles’.

Zero Kelvin temperature equals zero gas molecule kinetic energy.

At what temperature is zero Kelvin? -273°CTk

KEave

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°C

Kelvin temperature (K)

Celsius temperature

(°C)

-273°C

273K

Tk = Tc + 273K

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Converting temperatures

Celsius temperature

(°C)

Kelvin temperature

(K)

0

27

47

456

483

273

300

756

-226

183

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Pressure and particles

What causes pressure in gases?

In a sealed container, the particles repeatedly strike the walls of the container.

What happens if you increase the temperature?

This causes pressure.

gas gets hottermore kinetic energy

more collisions at greater speed

more pressure

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Particles animation

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Pressure(P) and temperature(T)

T

PP T

As long as it is Kelvin temperature

P – pressure (Pascals) T – Temperature(K)

P1/T1 = P2/T2

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A gas at a pressure of 50 Pa and a temperature of 40K is heated to a temperature of 120K in a sealed container. What is the new pressure of the gas?

P1/T1 = P2/T2

P2= T2(P1/T1)

P2= 120x(50/40)

P2= 150 Pa

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A gas at a pressure of 200 Pa and a temperature of 140K is heated to an unknown temperature in a sealed container. The new pressure is 6 000 Pa. What is the new temperature of the gas?

P1/T1 = P2/T2

T2= P2(T1/P1)

T2= 6 000x(140/200)

T2= 4 200 Pa

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Einstein

During nuclear reactions mass can be changed into energy.

This happens in stars and nuclear reactors, and nuclear fission bombs.

The amount of energy produced as mass is changed into energy is given by the formula:

Energy = mass change x (speed of light)2

Energy – J Mass – Kg Speed of light – ms-2

E = mc2

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A mass of 2 Kg is completely converted into energy. The speed of light is 3x108 ms-1.How much energy is released?

E = mc2

E = 2x(3x108)2

E = 1.8 x 1017 J

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Light

En

ergy le

vels

Electrons drop an energy level.

Light is emitted/absorbed?

Electrons gain an energy level.

Light is emitted/absorbed?

Electrons have discrete energy

levels

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Electron gun

cathode

grid

anodes

y-plates

x-plates

fluorescent screen

Can you label the parts of the gun?

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How does it work?

Hot metal filament emits electrons

The electrons are attracted to the anodes and accelerated

Electron beam passes through the X and Y plates

Electrons strike the fluorescent screen and seen as a spot of light

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KE=QV

You can treat the electron beam as a flow of electrons:

Kinetic energy = Charge x Voltage

KE=QV

Kinetic energy measured in Joules (J)

Charge measured in Coulombs (C)

Voltage measured in volts (V)

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Formula triangles

KE

Q V

x

Formula triangles help you to rearrange formula. The triangle for the kinetic energy for an electron beam is shown below:Whatever quantity you are trying to find cover it up and it will leave you with the calculation required.

So if you were trying to find charge, Q…..

…you would cover Q up…

…and you are left with the sum…

Q = KE

V

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Formula triangles

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Uses of electron beams?

Oscilloscopes

TV tubes

Monitors

X ray productionElectroplating

Combustion engines

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What are the units of pressure?

A. Metres

B. Joules

C. Newtons

D. Pascals

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What is 225K in Celsius temperature?

A. -48°C

B. 48°C

C. 498°C

D. -498°C

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What is 333°C in Kelvin temperature?

A. 606K

B. -606K

C. 60K

D. -60K

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A gas at a pressure of 60Pa at a temperature of 50K in a sealed container is compressed to a pressure of 480Pa. What is the new temperature of the gas?

A. 8K

B. 80K

C. 6.2K

D. 400K

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Which of the following is not a use of electron beams?

A. Oscilloscopes

B. Monitors

C. Spray painting

D. X ray production