# Junior cert Science

What type of circuit can be found in the home Ring circuit
How are lighting and ring circuits, series or parallel Parallel
what do you call a thin piece of wire that heats up and melts when a current above a certain value passes through it Fuse
If a circuit has a current of 7A passing through it, what fuse should be used 10A
What do you call the modern devices that house use now instead of fuses Circuit breakers
What colour is the positive live wire Brown
What colour is the negative neutral wire Blue
What colour is the earth wire Green and Yellow
What is the purpose of the earth wire It is a safety wire that carries live current to the ground if required
Why should you never overload a circuit can cause a fire
What is the unit of electrical power watt (W)
What is the watt a measure of How quickly an appliance converts electrical energy to other forms of energy
What is the ESB unit of electricity kilowatt hour (kWh)
How would you calculate the number of kilowatt hours used Number of kilowatts * number of hours
How would you calculate the cost of electricity Number of units * cost per unit
What is a direct current (d.c.) current that travels in one direction only
What is an alternating current (a.c.) Current that changes direction many times per second, like the ESB supply
How can alternating current be converted to direct current Using a rectifier
If an immersion heater has a power rating of 2000W, what is it rating in kW 2kW
If a 2kW heater is left running for 6 hours, how many units of electricity does it use 12units
If electricity costs 15c per unit, what does it cost to run the heater that uses 2 units every hour, if it is running for 6hours 0.15x2x6= 1.80

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