Electricity

Question 1

Power in electricity

Answer 1

Rate at which energy is converted from one form into another

Question 2

Power in electricity equations

Answer 2

Power (W) = energy (J) / time (s)
Power (W) = current (A) x p.d (V)
Power (W) = current^2 (A) x resistance (ohms)

Question 3

Two bulbs have the same brightness. Which bulb is more energy efficient, the 60W bulb or 15W bulb?

Answer 3

60W = 60 J/s
15W = 15J/s
Both bulbs are producing the same amount of light energy per second but the 60W bulb is producing more heat energy per second, therefore wasting more energy per second. Therefore 15W bulb is more efficient

Question 4

DC (direct current)

Answer 4

Always flows in one direction

Question 5

AC (alternating current)

Answer 5

Changes direction constantly

Question 6

Mains electricity

Answer 6

50Hz (50 cycles per second)
230V
AC

Question 7

Neutral wire

Answer 7

Blue, completes circuit

Question 8

Live wire

Answer 8

Brown, provides alternating p.d

Question 9

Earth wire

Answer 9

Green and yellow stripes, provides a low resistance path for current to flow through if there is a fault

Question 10

Electrical conductors

Answer 10

Allow charge to flow through easily (metals)

Question 11

Electrical insulators

Answer 11

Don’t allow charge to flow through easily (non-metals)