Energy and power of electricity and the national grid Flashcards

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1
Q

State the equation linking current, potential difference and power

A

Power= Current x potential difference

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2
Q

State the equation linking current, power and resistance

A

Power= current 2 x resistance

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3
Q

State the two most commonly wasted forms of energy

A

Thermal and sound

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4
Q

When energy is wasted what happens to it

A

It is dissipated into the environment

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5
Q

State the equation linking time power and energy

A

Energy=power x time

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6
Q

State the equation linking energy, potential difference and charge flow

A

Energy= Charge flow x potential difference

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7
Q

What is the national grid composed of ?

A

Cables and transformers linking power stations to consumers

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8
Q

What is the national grid used for

A

Suppling electricity to houses

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9
Q

State the effect of step up transformers on potential difference

A

Increases p.d

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10
Q

State the effect of step down transformers on potential difference

A

Decreases p.d

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11
Q

State the effect of step up transformers on current

A

Decreases current

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12
Q

State the effect of step down transformers on current

A

Increases current

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13
Q

Why are step up transformers used

A

To reduce energy loss for cables (thermal)

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14
Q

Why are step down transformers used

A

To reduce the potential difference to make it safe for domestic use

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15
Q

Why is the national grid efficient

A

Transformers reduce heat loss from wires when electricity travels long distance

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16
Q

If there are four times as many turns on the secondary coil as on the primary coil, then the voltage output on the secondary coil __________

A

will be four times the input voltage.

17
Q

A transformer can change the voltage (potential difference) in wires carrying _________

A

alternating currents.

18
Q

Step-up transformer

Ns _ Np .

A

>

19
Q

Step-down transformer

Ns _ Np .

A

<

20
Q

Vs=

A

(Vpx Ns) /Np

21
Q

Ns=

A

(VsxNp)/Vp

22
Q

Np=

A

(Vp/Ns)/Vs

23
Q

What term is used to describe when magnetic materials become magnets in a magnetic field?

A

induced magnetism

24
Q

What do we call a loop of wire that is coiled into a cylindrical shape?

A

Solenoid