12.1- CURRENT AND CHARGE

Question 1

What must a circuit be like to make an electric current pass round the circuit?

Answer 1

circuit must be complete + there must be source of p.d. i.e. battery in circuit

Question 2

What is the electric current?

Answer 2

rate of flow of charge in wire or component

Question 3

What is the current due to?

Answer 3

passage of charged particles

Question 4

What are the charged particles responsible for current referred to as?

Answer 4

charge carriers

Question 5

What are the charge carriers in metals?

Answer 5

conduction electrons

Question 6

What do the conduction electrons in metals do?

Answer 6

move about inside metal, repeatedly colliding with each other + fixed positive ions in metal

Question 7

What is the charge carried by when current is passed through a salt solution?

Answer 7

charge carried by ions

Question 8

What are ions?

Answer 8

charge atoms or molecules

Question 9

What is a simple test for conduction of electricity?

Answer 9

meter shows non-zero reading whenever any conducting material connected in circuit
battery forces charge carriers through conducting material + causes them to pass through battery + meter

Question 10

Simple test for conduction of electricity with metal?

Answer 10

electrons enter battery in positive terminal after passing through metal + ammeter, + leave at negative terminal to continue cycle again

Question 11

What is the convention for direction of current in a circuit?

Answer 11

from positive (+) to negative (-)

Question 12

What is the unit for current?

Answer 12

ampere (A)

Question 13

What is the unit for charge?

Answer 13

coulomb (C)

Question 14

Equation for change in charge? (with current)

Answer 14

ΔQ= IΔt

Question 15

What are the electrical terms materials can be classified in? (3)

Answer 15

conductors, insulators, or semiconductors

Question 16

What are electrons like in an insulator?

Answer 16

each electron attached to an atom + cannot move away from atom

Question 17

What happens when a voltage is applied across an insulator?

Answer 17

no current passes through insulator

Question 18

Why does no current passes through an insulator when a voltage is applied across it?

Answer 18

as no electrons can move through insulator

Question 19

What are electrons like in a metallic conductor?

Answer 19

most electrons attached to atoms but some delocalised- delocalised electrons are charge carriers in metal

Question 20

What happens when a voltage is applied across a metal?

Answer 20

conduction electrons attracted towards positive terminal of metal

Question 21

What happens to the number of charge carriers as temp increases in a semiconductor?

Answer 21

number of charge carriers increases with an increase of temp

Question 22

What happens to resistance as number of charge carriers increases with an increase of temp in semiconductors?

Answer 22

resistance of semiconductor decreases as temp raised

Question 23

What is a pure semiconducting material referred to as?

Answer 23

intrinsic semiconductor

Question 24

Why is a pure semiconducting material referred to as an intrinsic semiconductor?

Answer 24

as conduction due to electrons that break free from atoms of semiconductor