⚡ Electric Measurement — Part 2

E1 The Real Multimeter — Meet the Tool ENGAGE ▾

You are a real electrician. The circuit is already running — the battery is connected and current is flowing through the lamp right now. The multimeter is your measurement tool. Drag its probe wires to different points in the circuit to observe what the meter reads. The probes observe — they do not start or stop the current.

MULTIMETER
-.--
connect probes
MODE: —

🔴 Drag red probe · ⚫ Drag black probe · Current always flows — break wire to open circuit

🔑 Key insight: Every multimeter has a COM terminal (Common / Negative). The black probe always goes into COM, regardless of mode.

Q1 · What does COM stand for in a multimeter? 1 pt

A Copper Only Measurement

B Common (negative/ground) terminal

C Current Output Meter

D Calibration Output Mode

Q2 · When using a multimeter as an ammeter, where does the black probe go? 1 pt

A Into the "V" (voltage) terminal

B Into the "A" (ampere) terminal

C Always into COM, regardless of mode

D Anywhere — colour doesn't matter

How confident do you feel about the multimeter?

E2 Circuit Diagrams — Ammeter & Voltmeter Symbols EXPLORE ▾

Now we convert the real multimeter into circuit diagram symbols. The small black dot next to each symbol represents the COM probe connection point.

Ammeter (A) — series Voltmeter (V) — parallel COM point (●)

🔵 Ammeter in Series: Current passes through the ammeter — must be in the main wire.

🟡 Voltmeter in Parallel: Connects to both sides of the component being measured.

Q3 · How is an ammeter connected in a circuit? 1 pt

A In parallel across the component

B In series, in the main wire

C Connected to the positive terminal only

D Anywhere near the circuit

Q4 · The small black dot (●) near A or V represents… 1 pt

A A junction/node in the wire

B The COM (negative/ground) probe connection

C A resistor symbol

D The position of the battery

How confident are you with circuit diagram symbols?

E3 Readings & Rules — When Things Go Wrong EXPLAIN ▾

What does the meter tell you?

Ammeter reads 0 A
→ Circuit is open. No current can flow.

Voltmeter reads battery voltage
→ Measured component is open/broken.

Voltmeter reads 0 V
→ Both probes are on points at the same potential — no voltage difference to measure.

Ammeter reads very high
→ Possible short circuit.

🧮 Exercises

A lamp is connected to a 6 V battery. The circuit is closed and the ammeter reads 0.5 A. What voltage does the voltmeter read when placed across the lamp? (Hint: a single lamp in a closed circuit takes all the battery's voltage) V 2 pts

A circuit has a 9 V battery, a lamp, and a switch. The switch is OPEN. A voltmeter is placed across the open switch. What does it read? (Hint: in an open circuit, where does all the battery voltage appear?) V 2 pts

Q5 · An ammeter in a circuit with an open switch reads? 1 pt

A The maximum current the battery can supply

B 0 A — no current flows in an open circuit

C The battery voltage in amperes

D It doesn't matter — ammeters only work in closed circuits

How confident are you interpreting meter readings?

E4 🎮 Circuit Detective — Find the Fault! ELABORATE ▾

Use your virtual meters to identify what's happening in 5 different circuits. Two steps each round: measure first, then answer.

⚡ Circuit Detective

Round 1/5 ❤️ 3 Score 0/5

① Measure → ② Answer Click "Measure" to capture readings first!

AMMETER (A)

— A

VOLTMETER (V)

— V

Loading scenario...

What is happening in this circuit?

Red probe = + terminal Black probe = COM terminal

🏆 Bonus: Complete all 5 rounds with all 3 lives → earn +1 bonus point!

How was the detective challenge?

E5 Evaluate — Final Assessment & Submit EVALUATE ▾

Q6 · A voltmeter across an intact wire reads 0 V. Why? 1 pt

A The voltmeter is broken

B A plain wire has no voltage difference across it — both probe points are at the same potential

C Voltmeters only work with batteries

D Current is too low to measure

Q7 · A voltmeter across a burnt-out lamp reads 6 V (= battery voltage). Why? 1 pt

A The lamp is working normally and glowing brightly

B The broken filament acts as an open circuit — all voltage drops across it

C The ammeter is drawing extra current

D The voltmeter is connected in series

A parallel circuit has two branches connected to a 6 V battery. Both switches are ON. A voltmeter across Branch A reads 6 V. What does a voltmeter across Branch B read? (Hint: think about what is the same for every branch in a parallel circuit) V 2 pts

📝 Written Response 3 pts (teacher-graded)

Explain: Why is COM always connected to the negative probe, and what would happen if you swapped the probes into wrong terminals?

📊 Score Breakdown

Section	Component	Earned	Max
E1 Engage	Q1 + Q2	0	2
E2 Explore	Q3 + Q4	0	2
E3 Explain	Ex1 + Ex2 + Q5	0	5
E4 Game	Circuit Detective	0	5+1
E5 Evaluate	Q6 + Q7 + Ex3	0	4
E5 Written	Open response	—	3
AUTO TOTAL (raw)		0	18+1
SCORE /20		0	20

Grade Scale (auto-scored part)

A ≥ 17/20 B ≥ 14/20 C ≥ 11/20 D < 11/20 + 3 pts written (teacher-graded)

Your Results

0/20

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