Mains Electricity-O level

measure of power

• volt

• ohm

• watt

• amp

What is the power of a 20V bulb with 5A through it?

• 100W
• 100V
• 6.3W
• 6.3A

What is the current through a 11V bulb with a power of 99W?

• 9W
• 9A
• 60V
• 60A

A _________ is a plug or cartridge containing a strip of metal that melts when more than a specified amount of current passes through it.

• fuse
• breaker
• circuit
• panel

Which wire is connected to a fuse in a plug?

• Live

• Neutral

• Earth

• Positive

Which one is a Fuse?

• 
• 
• 
• 
• 

What is another Equation for Power?

• Power = Current / Potential Difference

• Power = Potential Difference / Current

• Power = Current x Potential Difference

What are the Equations for Energy Transferred? Choose 2

• Energy Transferred = Power x Time

• Energy Transferred = Power / Time

• Energy Transferred = Charge Flow x Potential Difference

• Energy Transferred = Charge Flow / Potential Difference

What advantage does a circuit-breaker have over a fuse in an electric circuit?

• A circuit-breaker provides an alternate route for the current to flow

• A circuit-breaker can be reset

• A fuse can be reset

• A fuse is more expensive

An appliance works at 3A. What is the best option for a fuse in the circuit connected to this appliance and why?

• 5A, so that the fuse does not blow when the appliance is used normally

• 7A, since it allows a current much larger than needed for the appliance to flow in the circuit

• 2A, so that the fuse blows when the appliance is used normally

• 3A, since the fuse blows at the same value of current that the appliance needs