7.9 Energy in circuits

Question 1

What is the equation relating energy transferred and current, p.d. and time?

Answer 1

Energcy transferred (joules) = current (amps) x p.d. (volts) x time (seconds)

E = I x V x t

Question 2

HOw do fuses work?

Answer 2

Fuses melt and break a circuit if the current gets too high (as it heats the fuse wire), preventing issues of high current (e.g. fires, electric shocks)

Question 3

How is energy wasted when electricitiy flows though a circuit? How could this be reduced?

Answer 3

Some electric energey is transferred to heat energy - the higher the current and resistance, the more energey is transferred to heat.

Using low-resstance wires, or transferring eneregy at a low current, helos minimise this.

Question 4

Give a useful application of electrical heating

Answer 4

Toasters.

Use high-resistance wires that heat up a lot when electricity us passed through it, so the wires can heat the bread