Electric current and Potential Difference

Question 1

Define electric current.

Answer 1

An electric current is the rate of flow of charged particles.

Question 2

What is the SI unit of current?

Answer 2

The SI unit of current is the ampere (A).

Question 3

Explain how a solution of sodium chloride dissolved in water can conduct electricity.

Answer 3

1. Dissolving sodium chloride in water produces positively charged sodium ions and negatively charged chlorine ions.
2. The ions are mobile and will allow a electric current to flow through it.

Question 4

What is the SI unit of charge?

Answer 4

The SI unit of charge is the coulomb (C).

Question 5

What is the charge on an electron?

Answer 5

The charge on an electron is 1.6 x 10^-19 C.

Question 6

What is the relationship between charge/C current/A and time/s.

Answer 6

Q = It

Question 7

Define 1 coulomb.

Answer 7

1 coulomb is the quantity of charge that passes through any section of a conductor in 1 second when a current of 1 ampere is flowing. 1 C = 1 As

Question 8

Explain what needs to be done in order for electrons to flow in a metal.

Answer 8

Energy must be supplied. In a simple circuit, an electric cell can be used to provide the energy needed to move the free electrons in the metal. The cell produces energy because of the chemical reactions taking place in it.

Question 9

Describe electron flow.

Answer 9

Electrons flow from the negative end of the cell through the conduction to the positive end.

Question 10

Describe conventional electric current.

Answer 10

This current flow is opposite in direction to electron flow. It can be thought of as going from the positive end of the cell through the conductor to the negative end.

Question 11

How are electrical currents measured?

Answer 11

Electrical currents are measured using an ammeter.

Question 12

How are ammeters connected in the circuit?

Answer 12

Ammeters are connected in series with the component.

Question 13

What is an ideal ammeter?

Answer 13

An ideal ammeter has zero resistance.

Question 14

Describe the energy changes that occur when charge passes through a filament lamp.

Answer 14

Energy is converted from electrical to light and thermal energy as it passes through the filament lamp.

Question 15

Describe the energy changes that occur when charge passes through a resistor.

Answer 15

Energy is converted from electrical to thermal energy.

Question 16

What cause an electric current to flow from one point to another.

Answer 16

A difference in electric potential between two points causes an electric current to flow from one point to another.

Question 17

Define electric potential.

Answer 17

Electric potential at a point in an electric field is the work done in moving unit positive charge from infinity to that point.

Question 18

What is the SI unit of electric potential and potential difference?

Answer 18

The SI unit of potential is the volt (V).

Question 19

Define potential difference.

Answer 19

The potential difference between two points in a circuit is the word done in moving unit positive charge from one point to another.

Question 20

How is potential difference measured.

Answer 20

Potential difference is measured with a voltmeter.

Question 21

How is the voltmeter connected in a circuit?

Answer 21

A voltmeter is connected in parallel with the component whose potential difference is being measure.

Question 22

What is an ideal voltmeter?

Answer 22

An ideal voltmeter has an infinite resistance.

Question 23

What is the relationship between potential difference/V, work done/J and charge/C?

Answer 23

V = W/Q

Question 24

Define 1 volt.

Answer 24

1 volt is defined as the potential difference between two points in a circuit when 1 joule is energy is converted when 1 coulomb of charge flows between the two points. 1 V = 1 J C^-1