Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

1.3Unit 9: Electricity and circuits

Measuring the flow of current — Cambridge Checkpoint Physics 0893 Revision Notes & Topical Questions

5 min read 8 parts Lesson 3 of 5 1 quiz

📚 Cambridge Checkpoint Physics 0893 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read
Lesson summary

1.3 Measuring the flow of current — CHECKPOINT PHYSICS 0893 notes: State the unit of current, read an ammeter, connect it in series and describe current in a series circuit.Faster electrons — a bigger current means the electrons move more quicklySlower electrons — a smaller curre…

  • Red terminal
  • Circuit symbol
  • Current rule
  • Slower electrons — a smaller current means the electrons move more slowly
  • Measuring — an ammeter measures current
  • Unit — current is measured in amps

Part 1 of 6Current and electron speed

Faster electrons
  • Faster electrons a bigger current means the electrons move more quickly
Slower electrons
  • Slower electrons a smaller current means the electrons move more slowly
Measuring
  • Measuring an ammeter measures current

Part 2 of 6Unit of current

Unit
  • Unit current is measured in amps
Symbol
A
Reading
  • Reading take the value from the ammeter scale and include the unit

Part 3 of 6Connecting an ammeter

Terminals
  • Terminals an ammeter has a red terminal and a black terminal
Red terminal
  • Red terminal it must be connected to the positive terminal of the power supply, directly or through other components
In series
In series connected end-to-end, one after another, with no branches
Position
  • Position an ammeter is always connected in series with the other components
Circuit symbol
  • Circuit symbol both ends are the same, so the red and black terminals are not shown

Part 4 of 6Series circuits

Same path
  • Same path in a series circuit the electrons have only one path to follow
Current rule
  • Current rule the current is the same at every point in a series circuit
Why
  • Why the electrons flow at the same speed in all the wires, so an ammeter reads the same at any position

Part 5 of 6Investigating current in a series circuit

1
Connect a cell, a switch and two lamps in series, without the ammeter.
2
Draw the circuit diagram and add arrows showing the direction of electron flow.
3
Predict whether the current will stay the same, decrease or increase round the circuit.
4
Place the ammeter at position X, close the switch and record the reading.
5
Open the switch, move the ammeter to Y and then Z, and record each reading.
6
Compare the three readings and conclude that the current is the same at every position.

Part 6 of 6More from the specification

More from the specification
Ammeter connection rule
  • An ammeter must always be connected in series with components so that the full circuit current flows directly through it.
Unit of current (Ampere)
  • Electric current is measured in amperes (A) or milliamperes (mA), representing charge flow rate in coulombs per second.
Conservation of current in series
  • Current is identical at every point in a single series loop;
    • charge is neither gained, accumulated, nor consumed.
Analogue ammeter scales
  • Reading calibrated dial divisions carefully to determine quantitative current values accurately.
Activity
  • Number of decays per second of a sample.

Key terms

TermMeaning
AmpUnit of current, symbol A.
AmmeterInstrument that measures current.
In seriesConnected end-to-end with no branches.
CurrentFlow of electrons.
TerminalConnection point on a component.

Avoid these mistakes

1
Connecting an ammeter in parallel with a component — it must be in series.
2
Thinking current is used up as it goes round a series circuit — it is the same everywhere.
3
Thinking a bigger current means slower electrons — electrons move faster for a bigger current.
4
Leaving out the unit in an answer — current is given in amps (A).

Last updated:

\n