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level: Electricity

Questions and Answers List

level questions: Electricity

QuestionAnswer
Energy transfers inside of a kettleElectric to thermal
Energy transfers inside of a fanElectric to kinetic
What is potential difference?Energy transferred per charge passed
How is energy transmitted across the National Grid?Transmits electricity at high p.d. (400 000V) and low current across the UK from power stations to homes and industry.
What do step-up transformers have?More turns on the secondary coil than the primary coil.
What do step-up transformers do?Increase the p.d to 400 000V, reducing current.
What do step-down transformers have?More turns on the primary coil than the secondary coil.
What do step-down transformers do?Reduce p.d from 400 000V, increasing current.
How is the efficiency of energy transfer increased in the National Grid?The current doesn't heat the cables as much as a higher current would, so less heat is loss by thermal dissipation.
What causes a static charge?A transfer of electrons between insulating materials rubbed together, leaving them oppositely charged.
After a polythene rod and a cloth duster are rubbed together which has which charge? What has happened?Rod- negative Cloth- positive Electrons transferred from cloth onto rod.
After an acetate rod and a cloth duster are rubbed together which has which charge? What has happened?Rod- positive Cloth- negative Electrons transferred from the rod to the cloth.
What happens to p.d. as electric charge builds on an object?It increases from 0V
How is a spark caused from the electric charge?When the p.d. between the object and the earth gets large enough, electrons can jump between the gap causing a spark.
Is electrostatic attraction/repulsion a contact or non-contact force?Non-contact
Where are electric fields found?Around any charged object
Which way do electric field lines point?Positive to negative
What do closer electric field lines show?A stronger electric field
What happens as you increase the distance between charged objects?The strength of field decreases and the force between them decreases
What do high p.d.s cause between charged and earthed objects?Strong electric fields
What does a strong field do to air particles?It removes electrons (ionises), allowing current to flow through it.