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Hint

1

AC current

changes direction and instantaneous value with time

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2

EMF

the energy supplied to each coulomb of charge passing through the battery.

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3

Lost volts

The potential difference across the internal resistor of a source of e.m.f.

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4

Internal resistance

resistance inside the source of electrical energy.

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5

terminal potential difference (t.p.d.)

Voltage that appears across the terminals of a source when the source is supplying a current to a circuit. It is the potential difference that appears in the circuit.

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6

short circuit

A connection that allows current to take the path of least resistance

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7

open circuit

an incomplete electrical circuit in which no current flows

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8

Information from a Vtpd vs Current Graph.

Y Intercept - EMF

X Intercept - Short Circuit Current

Gradient = -r

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9

1 Farad

1 coulomb of charge stored per unit volt

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10

Capacitance (C)

Measured in Farads (F)

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11

Charge (Q)

Measured in Coulombs (C)

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12

Area under a Q vs V graph.

Energy Stored in a capacitor.

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13

Voltage vs Time for Charging Capacitor

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14

Current vs Time for Charging Capacitor

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15

Voltage vs Time for Discharging Capacitor

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16

Current vs Time for discharging Capacitor

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17

Adding a resistor in series to an internal resistance circuit.

Resistance increases.

Current decreases.

Lost volts decrease.

VTPD increases

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18

Removing a resistor from a internal resistance circuit. Or adding in parallel.

Resistance decreases

Current increases

Lost volts increase

VTPD decreases

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19

Capacitor/Resistance Circuit - What happens when you increase resistance?

Initial Current reduces.

Longer time to charge.

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20

Capacitor/Resistance Circuit - What happens when you increase capacitance?

Longer time to charge.

Same final voltage.

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21

conduction band

A band higher in energy than the fully occupied valence band. Will have electrons free to move in this energy band.

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22

valence band

The highest energy band that is fully occupied.

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23

For conduction to occur you need

Free electrons, accessible empty states

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24

Conductivity increases with temperature increasing

Semiconductor

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25

Conductivity decreases with temperature increasing.

Conductor

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26

Has partially filled valence and conduction bands.

Metals (Conductors).

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27

Has a filled valence band.

Insulators.

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28

At room temperature there is enough energy to move electrons from valence to conduction band.

Semiconductor.

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29

Term to describe adding impurities to semiconductor.

Doping

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30

Why are semiconductors doped?

To increase conductivity.

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31

Negative terminal connected to N-Type

Positive terminal connected to P-Type

Forward bias

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32

Positive terminal connected to N-Type

Negative terminal connected to P-Type

Reverse bias

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33

Forward bias does what to the depletion layer?

Makes it smaller, reduces electric field

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34

Reverse bias does what to the depletion layer?

Makes it larger, increases electric field

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35

For an LED to light it needs to be in ...

Forward Bias

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36

For a solar cell to produce electricity it needs to be ...

Unbias

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37

When the LED is forward bias it works because ....

Voltage applied causes electron from the conduction band of the n type to move towards the conduction band of p type. Electrons fall from the conduction band to valence band, photon emitted.

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38

A solar cell works because...

Electrons gain/absorb energy from photons/light, electrons move form valence band to conduction band. Electrons move towards n-type semiconductor (producing a P.D.)

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