Electricity and Electrostatics Flashcards

1
Q

What is the charge on an

electron?

A

-1

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2
Q

What is the charge on a

proton?

A

+1

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3
Q

What is the charge on a

neutron?

A

0

/neutral

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4
Q

Why can electrons move between substances but protons cannot?

A

Because electrons are much lighter and if a proton moves between a substance then that would change its proton number which would change the element.

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5
Q

How can electrons be transferred?

A

By friction or by induction.

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6
Q

Why does a charged balloon stick to a neutral wall?

A

Because the electrons in the wall would be attracted/repelled by the electrons/protons in the balloon.

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7
Q

Define

electric field.

A

A region where a charged object will experience a force.

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8
Q

How are electrical fields drawn?

A

By considering it to consist of imaginary lines showing the direction of the force acting on a positive charge.

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9
Q

Where is the force exerted by a charged particle the greatest?

A

Close to the particle.

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10
Q

What does the density of field lines suggest?

A

The strength of the forces.

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11
Q

Describe a uniform field.

A

The strength and direction of the field is the same everywhere. So the lines are parrallel and evenly spaced.

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12
Q

Define

conduction.

A

The transfer of thermal energy by one particle bumping into another particle and transferring its kinetic energy.

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13
Q

Why is it important that the balloon is an insulator?

A

So that the electrons the balloon gains/loses stay in one area of the balloon and do not spread out. Resulting in an area of net negative/positive charge compared to the (relatively) neutral rest of the balloon.

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14
Q

What is the earth in physics.

A

An infinite electron donor/acceptor due to its large mass and electron quantity.

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15
Q

What would happen if you earthed a positively charged object?

A

The electrons would flow from the earth to the object.

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16
Q

What would happen if you earthed a negatively charged object?

A

The electrons would flow from the object to the earth.

17
Q

Why do sparks happen?

A

A positively charged object will try to grab electrons so that it can become neutral again. Sometimes this pull can be so strong that an electron from a nearby air molecule can be ripped out - leaving behind a positive ion. When this happens, a chain reaction causes lots of molecules to be ionised and a spark forms.

18
Q

Why do sparks appear in the way that they do?

A

When a spark happens, electrical potential energy is converted into light, thermal and sound energies.

19
Q

What is current?

A

The (rate of) flow of charge.

(/the rate of flow of charged particles)

20
Q

What is charge measured in?

A

C, coulombs

21
Q

What is current measured in?

22
Q

What is time measured in?

A

s, seconds

23
Q

What equation links current, charge and time?

(I, Q, t)

A

current = charge/time

I = Q/t

or Q = It

24
Q

What direction is electron flow?

A

negative to positive

25
What direction is conventional current?
positive to negative
26
What is an amp?
1 amp is 1 coulomb per second | 1A = 1C/s
27
What is a volt?
1 volt is 1 joule of energy per coulomb of charge | 1V = 1J/C
28
What equation links energy, voltage and charge? | (E, V, Q)
energy = voltage x charge | E = VQ
29
What equation links energy, voltage, current and time? | (E, V, I, t)
energy = voltage x current x time | E = VIt ## Footnote evit, ewit, evict / energy from vitamins
30
Define power
rate of energy transferred
31
What equation links power, energy and time? | (P, E, t)
power = energy/time | P = E/t
32
What equation links power, current and voltage? | (P, I, V)
power = current x voltage | P = IV ## Footnote piv, pov
33
What is Ohm's Law? | (V, I, R)
voltage = current x resistance | V = IR
34
What equation links power, current and resistance? | (P, I, R)
power = current^2 x resistance | P = I^2 R ## Footnote PIIR, peer
35
What equation links power, voltage and resistance? | (P, V, R)
power = voltage^2 / resistance | P = (V^2) / R