Electricity - energy and voltage in circuits

Question 1

charge

Answer 1

measured in coulombs

Question 2

current

Answer 2

-measured in amperes
-how many charges flow through a point each second.
- is conserved, can never be used up

Question 3

amperes

Answer 3

1 ampere = 1 coulomb of charge per second

Question 4

current =

Answer 4

charge / time

Question 5

potential difference

Answer 5

• voltage
  - energy gained or lost per each charge
• 1 volt = 1 Joule per Coulomb of charge
• shared equally between components
• not conserved

Question 6

resistance

Answer 6

• the ability of a component to slow down a current by removing energy from the current
• measured in ohms (omega symbol)
• greater the resistance, the lower the current

Question 7

voltage, current and resistance

Answer 7

voltage = current x resistance
V = IR

Question 8

where does resistance come from

Answer 8

• delocalised electrons and positively charged ions
• collide causing the electrons to slow down
• this causes the ions to vibrate and heat up
  higher thermal energy leads to more collisions
• leads to resistance

Question 9

temperature and resistance

Answer 9

resistance changes with temperature (increases as temperature increases)

Question 10

Ohm’s law

Answer 10

the voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions, such as temperature, remain constant