Charge and current

Question 1

What is electric current?

Answer 1

The net flow of charged particles

Question 2

How is an electric current achieved in a metal?

Answer 2

Electric currents move through metals using the delocalised electrons formed through metallic bonding

Question 3

How is an electric current achieved in an electrolyte

Answer 3

Electric currents move through electrolytes using the movement of charged particles, called ions.

Question 4

How does conventional current differ from the flow of electrons in a circuit?

Answer 4

conventional current travels from positive to negative, whereas the flow of electrons is from negative to positive

Question 5

State the equation for charge

Answer 5

Change in charge (Coulombs) = Change in current (amps) X Time (seconds)

Question 6

Define the coulomb

Answer 6

One coulomb is the amount of charge that flows when there is a current of one ampere for one second

Question 7

How can an ammeter be used to measure the current in a circuit?

Answer 7

The ammeter is placed in series with the circuit to measure is current

Question 8

What is the elementary charge of a particle?

Answer 8

e = 1.6x10^-19

Question 9

Describe kirchhoff’s first law

Answer 9

In a parallel circuit, all the current entering a junction leaves the junction. It states that current is always conserved.

Question 10

State the equation for average drift velocity

Answer 10

I=Anev
Where I = current
A = cross sectional area of wire
n = number density of the metal
e =elementary charge 
v = average drift velocity

Question 11

What is the difference in n between conductors, semiconductors and insulators

Answer 11

In conductors n = 10^28
Semiconductors n =10^23
insulators n = 0