Electricity

Question 1

Uses of static electricity

Answer 1

Spray paint-
The droplets are positively charged therefore they repel each other and form a fine spray, the object either is neutral or negatively charged so the droplets get attracted to it and get into small places and tight corners.

Inkjet printers-
Spray drops of ink onto page, directed using two oppositely charged plates, voltage on plates can easily be swapped or varied.

Question 2

series circuit rules

Answer 2

• current same
• voltage shared, add voltage to get total.
• add resistant to get total resistance

Question 3

parallel circuit rules

Answer 3

• current shared, add current to get total.
• voltage the same
• add 1/resistance then turn the fraction around to get total resistance.

Question 4

rules of thermistors and LDR

Answer 4

• as temperature increases, resistance decreases.
• for fixed voltage, current increases as temperature rise
• as light levels increase, resistance decreases
• graphs: resistance on Y-axis

Question 5

rules of light bulb

Answer 5

• doesn’t obey Ohms law
• as filament gets hot resistance increases
• graph: voltage on Y-axis, current on X-axis. line starts at origin and gradient slowly get steeper

Question 6

fixed resistor output graph

Answer 6

• proportional

- slope of graph gives resistance. voltage on Y-axis, current on X-axis.

Question 7

different fuses

Answer 7

1A, 3A, 5A, 13A

Question 8

3 core cables in a plug

Answer 8

green = earth wire
brown = live wire
blue = neutral

Question 9

causes of electric shocks

Answer 9

damaged plug, overheating, frayed cables, damaged insulation