Physics 2 - Particles at Work (P4 - P7) Flashcards by Indrought Unknown

What are the two charges and how do they attract.

Positive and Negative. Opposite charges attract, like charges repel.

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What is the equation for charge flow?

Charge flow (coulombs C) = Current I (Amperes A) x Time taken (seconds)

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What is the size of the electric current?

The rate of flow of charge.

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What is the equation for the electric current of a circuit?

Current (Amperes A) = Charge flow (Coulombs C) / time taken (Seconds)

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What is the equation for potential difference across a component?

Potential difference (Volts V) = Energy transferred (Joules J) / Charge (Coulombs C)

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What is Ohm’s law?

The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.

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What is the equation for resistance of an appliance?

Resistance (Ohms Ω) = potential difference (Volts V) / Current (Amperes A)

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What happens to a thermistor if its temperature increases?

Resistance decreases

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What happens if an LDR’s (Light dependent diode resistor) light intensity increases?

Resistance decreases.

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What is the equation for the total resistance of a circuit?

Total resitance = R1 + R2

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What two wires do all mains circuits have?

Live and neutral

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What is the equation for the frequency of an a.c supply?

Frequency = 1 / time taken for 1 cycle

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Name the three wires in a three pin plug and their colours.

Live = Brown
Earth = Yellow and Green
Neutral = Blue

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What are the three Current limits for fuses?

3A, 5A and 13 A fuses.

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What is the equation for energy transferred to a device?

Energy (J) = Power (Watts W) x Time (Seconds)

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What is the unit for density?

Kilogram per cubic metre kg/m(cubed)

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What is the equation for density?

density p = mass m / volume V

kg/m(cubed) = kg / metres cubed

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What type of objects float in water?

Ones with lower density than water.

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What will an object with a lower density than water do in water?

Float

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Does a substance’s mass change when it changes state? Why?

No because the number of particles stays the same.

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What does the flat section of a temperature-time graph give?

The melting point or the boiling point of the substance.

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What is required to melt a solid or boil a liquid?

Energy

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What does increasing the temperature of a substance do to its internal energy?

Increases it.

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What causes the pressure of a gas on a surface?

The particles of the gas repeatedly hitting the surface.

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What is the specific latent heat of fusion?

The energy required to change the state of 1kg of the substance from solid to liquid at its melting point.

What is the unit for specific latent heat of fusion?

Joules per kg J/Kg

What is the equation for specific latent heat of fusion?

Specific latent heat of fusion L = Energy E / Mass M | J/Kg = J / Kg

What is latent heat?

The energy needed for a substance to change its state without changing its temperature.

How can the specific latent heat of ice be measured?

Using a low-voltage heater to melt the ice.

What happens when the temperature of a gas in a sealed container is increased?

The pressure of the gas increases.

Why does the pressure of the gas increase when its temperature is increased within a sealed container? (2 Reasons)

- The molecules move faster so they hit the surfaces with more force. - The number of impacts per second of gas molecules on the surfaces of a sealed container increases, so the total force of the impacts increases.

What is Boyle's law?

For a fixed mass of gas at constant temperature the pressure multiplied by the volume is always constant.

What can happen if a gas is compressed rapidly?

The temperature can increase because work is done on it and the the energy isn't transferred quickly enough to its surroundings.

What does a radioactive substance contain?

Unstable nuclei that become stable by emitting radiation

What are the three main types of radiation from radioactive substances?

α - Alpha particles β - Beta particles γ - Gamma particles

Can you predict radioactive decay?

What do radioactive decay sources emit?

Alpha, Beta and Gamma radiation.

Which radiation has the highest penetration power?

Gamma

What did Rutherford find when he used alpha particles to probe inside atoms?

The alpha particles scattered through large angles.

Where is most of an atom's mass located?

The nucleus.

What is the plum pudding model?

A model of how scientists thought the structure of an atom was before 1914

What could the plum pudding model not explain about alpha particles?

Why some alpha particles were scattered through large angles.

What model of an atom explained why some alpha particles scattered through large angles?

The nuclear model

What is radioactive decay?

The release of radiation from a radioactive substance.

What are isotopes of an element?

Atoms with the same number of protons but different numbers of neutrons. This gives them the same atomic number but different mass numbers.

What change does alpha decay make to the nucleus?

Nucleus loses 2 protons and 2 neutrons.

What change does beta decay make to the nucleus?

A neutron in the nucleus changes into a proton.

What particle is emitted in alpha decay?

2 protons and 2 neutrons emitted as an alpha particle

What particle is emitted in beta decay?

An electron is created in the nucleus and instantly emitted.

What is the equation for Alpha decay?

TBC (KP Pg97)

What is the equation for beta decay?

TBC (KP Pg97)

What is the range of alpha radiation?

A few centimetres in air.

Which radiation has the lowest penetration power and can be stopped by a piece of paper?

Alpha radiation.

What does alpha radiation consist of?

Particles, each composed of two protons and two neutrons.

Which radiation has the highest ionising power?

Alpha radiation.

Which radiation has the median penetration power and can be stopped by a sheet of metal?

Beta radiation.

What is the range of Beta radiation?

About one metre in air.

What does Beta radiation consist of?

Fast-moving electrons emitted from the nucleus.

Which radiation has the median ionising power?

Beta radiation.

Which radiation has the highest penetration power and can be stopped by thick lead?

Gamma radiation.

What is the range of gamma radiation?

Unlimited in air.

What does Gamma radiation consist of?

Electromagnetic radiation.

What do alpha, beta and gamma radiation do when they pass through a substance?

Ionise them. Ionising in a living cell can damage or kill the cell.

What is the half life of a radioactive isotope?

The average time it takes for the number of nuclei of the isotope in a sample to halve.

What happens to the count rate of a Geiger counter as the activity of the source decreases?

It decreases.

What influences the count rate of a Geiger counter?

Activity of a radioactive source.

What happens to the number of atoms of a radioactive isotope and the count rate every half life?

They decrease by half. | Use decreasing asymptotically for extra cred

Equation for count rate after n Half-lives?

Count rate after n half-lives = Initial count rate / 2(to the n)

How are radioactive isotopes used in medicine?

They are used for medical imaging, treatment of cancer, and as tracers to monitor organs.

What does the usefulness of a radioactive isotope depend on? (Two things)

- Its half life | - The type of radiation it emits.

What can a gamma beam or a radioactive implant be used in the treatment of cancer?

It can destroy cancer cells in a tumour.

What is nuclear fission?

The splitting of an atom's nucleus into two smaller nuclei and the release of two or three neutrons and energy.

When does induced fission occur?

When a neutron is absorbed by a uranium-235 nucleus or a plutonium-239 nucleus and the nucleus splits. Spontaneous fission is when no neutron is absorbed.

When does a chain reaction occur in a nuclear reactor?

When each fission event causes further fission events.

What is nuclear fusion?

The process of forcing the nuclei of two atoms close enough together so that they forma a singe larger nucleus.

How can nuclear fusion be brought about?

By making two light nuclei collide at very high speed.

What happens when nuclei are fused together?

Energy is released. This is how the Sun's core releases energy.

What conditions are required for a fusion reactor to execute fusion?

Very high temperatures as the nuclei to be fused are difficult to contain.

What is Radon gas and what does it tend to do?

It is an alpha-emitting isotope that seeps into houses through the ground in some areas.

What is nuclear waste and why is it dangerous?

A substance containing many different radioactive isotopes that emit nuclear radiation for many years. The radiation is dangerous because it can cause cancer.