Current, Potential Difference And Resistance Flashcards

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0
Q

Give an example do current in a wire

A

Like WATER flowing in a PIPE

The amount of water that flows depends on the flow rate and the time

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1
Q

What is current

A

Rate of flow of charge

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2
Q

What is the equation linking current to charge and time

A

I=Q/T

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3
Q

What direction does conventional current flow

A

From + to -

The OPPOSITE way from ELECTRON flow

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4
Q

What is one coulomb defined as

A

The amount of CHARGE that passes in 1 SECONDS when the CURRENT is 1 amperes

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5
Q

What is the potential difference defined as

A

Energy converted per unit charge moved

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6
Q

To make electric charge flow through a conductor what do you need to do on it

A

Work

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7
Q

What is the pd in the water analogy

A

The pressure that’s forcing water along the pipe

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8
Q

What is the equation linking voltage to energy and charge

A

V=W/Q

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9
Q

When is the potential difference across a component 1 volt

A

When you convert 1 joule of energy moving 1 coulomb of charge through the component

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10
Q

How much current you get for a particular pd depends on heat

A

The resistance of the component

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11
Q

What can you think of a components resistance as

A

A measure of how DIFFICULT it is to get a CURRENT to FLOW through it

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12
Q

What is the equation which links resistance to voltage and current

A

R=V/I

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13
Q

When does a component have a distance of 1

A

If it’s pd of 1V makes a current of 1A flow through it

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14
Q

For an ohmic conductor what is constant

A

The resistance

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15
Q

What is ohm’s law

A

Provided the TEMPERATURE is constant, the CURRENT through an ohmic conductor is DIRECTLY proportional to the PD across it

16
Q

What are the conductors which obey ohms law called

A

Ohmic conductors (mostly metals)

17
Q

What does the graph of an ohmic conductor show when you plot voltage against current

A
Straight line (origin) 
Double pd double current- directly proportional 
Resistance constant - gradient always fixed
18
Q

What will have a significant effect on resistance (resistivity changes)

A

Light level

Temperature

19
Q

What is internal resistance

A

Loss of pd per unit current