Electrical Energy In Devices

Question 1

Whenever a charge flows, it had to overcome the resistance of the circuits, this requires energy, therefore:

Answer 1

• work is done when charge flows

- the amount of work done depends on the amount of change that flows and the potential difference

Question 2

Equation for energy transferred

Answer 2

• power x time

- charge flow x Potential diff

Question 3

What does the energy transferred by an appliance depend on

Answer 3

Power and time it is on for

Question 4

Power stations in national grid

Answer 4

• transfers energy supply into electrical energy

- using a smaller number of large power stations is more efficient that building multiple small, local ones

Question 5

Why is is more efficient to build a small number of large power stations than multiple small ones

Answer 5

• most power plants use steam turbines, which are more efficient at higher steam temp
• so bigger the plant, bigger the boiler, so higher the steam temp

Question 6

Step up transformers

Answer 6

• increase the potential difference from power station to transmission cables
• this reduces current and reduced the beating effect which REDUCES ENERGY LOSS

Question 7

Transmission cables

Answer 7

-Transfer electricity

Question 8

Step down transformers

Answer 8

-reduces potential difference from transmission cables to a much lower value for domestic use