Current - Voltage

Question 1

what is current?

Answer 1

• the rate of flow of charge ( A )

Question 2

what is 1 amp?

Answer 2

1 amp is equivalent to a charge of 1 Coulomb flowing in one second

1A = 1C/s

Question 3

what is current in electric circuits?

Answer 3

• the flow of electrons

Question 4

what is conventional current?

Answer 4

• the flow of positive charge

Question 5

what is potential difference?

Answer 5

• electrical work done per unit of charge flowing between two points

Question 6

what is 1 volt?

Answer 6

1 volt is equivalent to the transfer of 1 joule of electrical energy by 1 Coulomb of charge

1V = 1J/C

Question 7

what happens as electrons flow through a cell?

Answer 7

• they gain energy
• in a Xv cell, every coulomb of charge passing through gains Xj of energy

Question 8

what happens as electrons flow through a circuit?

Answer 8

• they lose energy
• after leaving a Xv cell, every coulomb of charge will transfer Xj of energy to waste and components

Question 9

what is resistance?

Answer 9

• a measure of how much the material opposes the flow of electric current
• measured in ohms

Question 10

what is a resistance of 1 ohm?

Answer 10

• equivalent to a potential difference across a component of 1V which produces a current of 1A through it

Question 11

what is Ohm’s Law?

Answer 11

Ohms Law states that for a conductor at a constant temperature, the current through it is directly proportional to the potential difference across it

Question 12

how do can you tell if an electrical component follows ohms law?

Answer 12

• straight line through the origin graphically

Question 13

explain the I-V graph for a filament lamp

Answer 13

• obeys ohms law for small voltages
• as current increases, temperature of filament increases
• since filament is a metal, higher temperature causes an increase in resistance
• resistance opposes current, causing current to increase at a slower rate

Question 15

what is a semiconductor diode used for?

Answer 15

• prevents backflow of current