chapter 16 - current electricity

Question 1

electric current

Answer 1

rate of flow of electric charge

Question 2

conventional current

Answer 2

flow of positive charges from the positive terminal to the negative terminal of the battery

Question 3

potential difference

Answer 3

work done per unit charge in driving charges through the component

Question 4

electromotive force

Answer 4

work done by the source in driving a unit charge around a complete circuit

Question 5

resistance

Answer 5

ratio of potential difference V across to the current I flowing through the component

Question 6

ohm’s law

Answer 6

the current passing through a metallic conductor is directly proportional to the potential difference across it, provided that physical coditions remain constant

Question 7

current formula

Answer 7

current (A) = charge (C) / time (s)

Question 8

p.d. and emf. formula

Answer 8

potential difference (V) = work done (J) / charge (C)

electromotive force (V) = work done (J) / charge (C)

Question 9

change is resistance of filament bulb

Answer 9

temperature increase, resistance increase

Question 10

change in resistance of thermistors

Answer 10

temperature increase, resistance decrease

Question 11

change in resistance of semiconductor diode

Answer 11

temperature increase, resistance decreases

Question 12

series vs parallel circuit

Answer 12

in a series circuit : total current drawn from the cells will be more, and hence bulb connected across a series circuit will be brighter / cells last for a short time

in a parallel circuit : total current drawn from cells will be lesser and hence bulb connected across a parallel circuit will be of normal brightness like using a single cell / cells last for a longer time