Question | Answer |
What happens when you move a magnet near a wire? | An induced current is produced |
What happens when you move a wire near a magnet? | An induced current is produced |
What is an induced current? | The current produced when a magnet moves near a wire (or vice-versa) |
Name 3 ways of increasing an induced current | more coil on the wire; a stronger magnet;moving the wire (or the magnet) faster |
What is direct current (DC)? | A current that flows always in the SAME direction. |
Name objects that use direct current | Torches, wind up radios. |
What is alternating current (AC)? | A current that CHANGES direction many times per second |
What type of magnets are used in power stations? Why? | Electromagnets are used because they can be made to be really strong magnets (much stronger than "natural" magnets) |
What is inside a generator? | A coil wound up around an iron core; the coil turns around permanent magnets. |
How can you reverse the direction of an induced current? | Swap the magnet around; or make it go in the other direction |
What type of current is produced in power stations? | Alternating current |
What is the voltage produced in power stations? | 25 000V (aka 25 kV) |
What is the voltage when transported in transmission lines? | 400 000V (aka 400kV) |
What is the voltage used at home? | 230V |
Why is voltage increased before being sent through the National Grid? | So that less energy is wasted in heat during transport. |
What happens when electricity is passing through a wire? | The wire heats up |
What is used to increase the voltage? | A step-up transformer |
What is used to decrease the voltage? | A step-down transformer |
A transformer has 100turns of wire in the primary coil and 20 in the secondary coil. If you input 20V, what will be the voltage coming out? | Four |
A laptop runs on the mains (230V) but only needs 20V supply. How many coils in teh secondary coil, if the transformer has 100coils in the primary coil? | Nine |
Why are the transmission lines placed so high | Because the voltage could kill you |
Why are birds not electrocuted? | Both their feet are at the same voltage |
Describe the stages electricity is transmitted to your homes | Power stations generated electricity; a step-up transformer raises the voltage; the current goes through transmission lines; a step-down transformer reduces the voltage before the current arrives to our homes. |
Describe the difference between direct current and alternating current. | |
The output from the solar panel is 60 V.
State why a transformer cannot be used to increase this voltage. | |
Explain why using solar panels to generate electricity for the National Grid
benefits the environment. | |
The cost of the solar panel is £4800.
The solar panel supplies an average of 800 kW h of electrical energy to the
National Grid each year. The homeowner is paid 40p for each kW h of energy supplied to the National Grid. Calculate the payback time. | |