Mains Electricity Flashcards

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1
Q

The formula for calculating electrical power is:

A

Power = Current x Voltage or P = IV Where I – current in amps (A) V – voltage in volts (V)

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2
Q

A bulb operates at 230V. The current is 0.08A. Calculate the power of the bulb.

A

P = IV P = 230 x 0.08 = 18.4 W (this would probably be an energy-saving bulb)

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3
Q

A hairdryer has a rating of 2kW. What current does it use?

A

P = IV I = P/V I = 2000/230 I = 8.7A

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4
Q

A power supply produces a current of 0.5A and has a power output of 2.5W. Calculate its voltage output.

A

P = IV V = P/I V = 2.5/0.5 V = 5V

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5
Q

A pair of curling tongs is rated at 1kW. Calculate the current it uses.

A

P = IV I = P/V I = 1000/230 I = 4.35A

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6
Q

A current of 0.5A flows through a power supply producing 12V. Calculate the output power.

A

P = IV P = 12 x 0.5 P = 6 W

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7
Q

Calculate the power of an electric can opener that uses 0.2 A.

A

P = IV P = 230 x 0.2 P = 46 W

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8
Q

Two equations for calcultaing Energy

A

E = IVt Where I – current in amps (A) V – voltage in volts (V) t – time of flow in seconds (s) E – energy used in joules (J) Notice that: P = IV So we can replace the It in the equation above with: E = Pt

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9
Q

Names 5 Electrical Hazards

A
  • Frayed Cables
  • Long cables
  • Damaged Plugs
  • Water
  • Metal Objects
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10
Q

What wire is connected to the metal casings of appliances?
Explain Why

A

The Earth wire

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11
Q

What size of fuse would you use for an appliance rated at 2.5 kW?

A

13 A

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12
Q

What size of fuse would you use for an appliance rated at 500W?

A

3 A

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13
Q

What does this symbol mean?

A

Double Insulated

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14
Q

When electricity flows in one direction only then the circuit is using

A

DC

Direct Current

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15
Q

When a circuit has a current flow that is constantly changing direction then the circuit is using

A

AC

alternating Current

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