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Physics > Energy, Electricity And Electrostatics > Flashcards

Energy, Electricity And Electrostatics Flashcards

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1
Q

What are changes in kinetic, gravitational potential, elastic, nuclear, and internal energy a resultant from?

A

An event or process

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2
Q

When is energy transferred?

A

During events and processes

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3
Q

How is energy transferred?

A
  • Electrical currents (electrical working)
  • Forces (mechanical working)
  • Heating
  • Waves
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4
Q

What is the principal of conversation of energy?

A

That energy is neither created or destroyed

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5
Q

Equation for kinetic energy is:

A

1/2mv^2

M = mass

V = velocity

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6
Q

Equation in change of gravitational potential energy is:

A

Gravitational potential energy = mg(change in)h

M = mass

G = gravity

H = height

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7
Q

What happens to energy during an event or process?

A

Energy tends to become more spread out among objects and surroundings (dissipated)

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8
Q

How is energy obtained from chemical energy stored in fuel?

A

Fossil fuel power plants burn coal or oil to create heat which is in turn used to generate steam to drive turbines which creates electricity

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9
Q

How is energy obtained from waves and tide

A

Tidal energy is created using the movements of our tides and oceans, where the intensity of the water from the rise and fall of our tides is a form of kinetic energy.

The movement of water pushes a turbine which hens forth generates energy

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10
Q

How is energy obtained from hydroelectric dams?

A

Water flows through a pipe and turns a turbine, spinning a generator and therefore producing energy,

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11
Q

How is energy obtained from geothermal resources?

A

Radioactive decay of these substances releases heat energy, which warms up the rocks.

In volcanic areas, the rocks may heat water so that it rises to the surface naturally as hot water and steam.

Here the steam can be used to drive turbines and electricity generators.

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12
Q

How is energy obtained by nuclear fission?

A

During nuclear fission, a neutron collides with a uranium atom and splits it, releasing a large amount of energy in the form of heat and radiation.

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13
Q

How is energy obtained from heat light from the sun?

A

The sun generates energy from a process called nuclear fusion.

During nuclear fusion, the high pressure and temperature in the sun’s core cause nuclei to separate from their electrons.

Hydrogen nuclei fuse to form one helium atom.

During the fusion process, radiant energy is released.

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14
Q

How is energy obtained by wind?

A

Wind pushes turbines creating energy

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15
Q

The sun is the source of all our energy resources except for geothermal, nuclear and tidal, true or false?

A

True

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16
Q

How is energy released from the sun?

A

Through the process of nuclear fission

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17
Q

What is the equation for efficiency of energy?

A

(Useful energy output/energy input) x 100

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18
Q

What is the equation for efficiency of power?

A

(Useful power output/power input) x 100

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19
Q

What is work done?

A

Energy transferred

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20
Q

What is a diode?

A

They’re a part of a circuit that lets through current depending on which way they’re facing

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21
Q

What is a thermistor

A

Thermistors change resistance depending on the surrounding temperature

When there is a HOT thermistor, there is a SMALL resistance

When there is a COLD thermistor, there is a LARGE resistance

This is different to a bulb where as the temperature of the bulb increases so does the resistance

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22
Q

What is ‘potential difference’ a name for

A

Voltage

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23
Q

Two resistors are in parallel in a circuit, how would you calculate the total resistance of the two resistors?

A

Rt = (R1 x R2) / (R1 + R2)

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24
Q

When two resistors are in SERIES you

A

add them together

25
Q

What is a variable resistor?

A

A variable resistor is a resistor of which the electric resistance value can be adjusted

26
Q

What is power?

A

Power is the RATE of TRANSFER of ENERGY (rate of doing work)

27
Q

What is an equation for power (P) using work (W) and time (t)

A

P = W/t

28
Q

What causes resistance in a metal conductor?

A

The resistance of a metal conductor is due to collisions between the free electrons of the electric current and the metal ions of the wire

29
Q

What happens to a metal when the amount of amps passing through a circuit increases?

A

When the temperature of a metal conductor increases, the ions of the metal vibrate more vigorously.

This increases the number of collisions between the free electrons and the ions.

Hence, for a metal, resistance increases with increasing temperature.

Often the increase in temperature is caused by an increase in current.

An example is a filament lamp.

As current increases, the filament gets hotter and the resistance of the bulb increases.

30
Q

What does “A” symbolise

A

Current

31
Q

What is current?

A

The rate at which electrons flow past a point in a complete electrical circuit

32
Q

What is voltage?

A

Voltage is the pressure from an electrical circuit’s power source that pushes current through a conducting loop, enabling it to do work such as illuminating a light.

33
Q

What are some rules on OHMS LAW

A
  • ALL conductors show SOME OPPOSITION to electric CURRENT.
  • This opposition to current is called RESISTANCE
  • A GOOD conductor has LOW resistance.
  • A POOR conductor, or insulator, has HIGH resistance.
  • The two main ways of INCREASING the current in an electrical circuit are by INCREASING the VOLTAGE or by DECREASING the RESISTANCE.
34
Q

What happens when you increase the number of lamps in a circuit?

A

If you increase the number of lamps in a series circuit, there will be less current.

The lamps resist the current, so if you put more lamps into the circuit, there is more resistance.

35
Q

How could you change the resistance without changing the current or voltage of the circuit?

A

You could increase or decrease the resistance in a circuit by using a variable resistor (a box with an arrow going through it)

36
Q

When plotting a resistance graph, which axis should current and voltage be on?

A

X - CURRENT (A)

Y - VOLTAGE (V)

37
Q

What the equation for voltage, current and resistance?

A

V = IR

I = V/R

R = V/I

38
Q

What is an equation for power using current (I) and resistance (R)

A

P = I x I X R

39
Q

What is an equation for power using Voltage (V) and resistance (R)

A

P = V^2 / R

40
Q

What is an equation for amps using charge (Q) and time (s)

A

I = Q / t

41
Q

What is an equation for power using current (I) and voltage (V)

A

P = I x V

42
Q

Units for potential difference /emf

A

V

43
Q

Units for charge

A

C

44
Q

What is charge?

A

Charge is a property of a body which experiences a force in an electric field.

45
Q

What is an electric field?

A

An electric field is a region where charges experience a force.

Fields are usually shown as diagrams with arrows: The direction of the arrow shows the way a positive charge will be pushed.

The closer together the arrows are, the stronger the field and the greater the force experienced by charges in that field.

46
Q

What experiment can be used to determine resistance in a circuit

A

The magnitude of resistance can be measured by different methods.

One method is to measure the voltage drop V across a resistance n a circuit with a voltmeter and the current I through the resistance with an ammeter.

47
Q

What proportionality are length of wire and resistance?

A

Directionally proportional

48
Q

What proportionality is cross sectional area of wire and resistance?

A

Inversely proportional (however it’s important to note when doubling the cross sectional area you quarter the resistance and so forth)

49
Q

Equation for energy

A

E = IVt

50
Q

What causes current in metals?

A

Flow of electrons

51
Q

What is conventional current?

A

Conventional current is the flow of a positive charge from positive to negative and is the reverse of real electron flow

52
Q

Work done equation using force and distance

A

W = Fd = (change) E

53
Q

What is a vector

A

A measurement consisting of direction and magnitude (size or amount of Newton’s)

54
Q

What is a scalar?

A

A measurement consisting of direction

55
Q

What force causes charging?

A

Friction

56
Q

Two positively charged objects are next to each over, will they attract or repel?

A

Repel

57
Q

1V = 1J/C

A

Yuh

58
Q

When adding 3 cells, each with a voltage of 1.5V, in series, what happens?

A

The cells add up to 4.5 V

59
Q

What is the effect of adding cells in parallel on the PD and current in a circuit

A

The current and PD don’t change

Physics (4 decks)

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