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QuizReal resistors: values, codes and tolerance · 6 min

Quiz: real resistors

7 questions. Answer each one, then open Show the answer to check yourself. In Litmux Academy the quiz is marked and counts towards your certificate.

Question 1Brown, black, red, gold is:

  1. 100 Ω
  2. 1 kΩ
  3. 10 kΩ
  4. 102 Ω
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Answer: B. 1 kΩ

1, 0, × 100 = 1000 Ω ±5 %.

Question 2An SMD resistor is marked 473. Its value is:

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Answer: 47000 Ω

47 × 10³ = 47 kΩ.

Question 3What does 4R7 mean on a parts list?

  1. 4.7 kΩ
  2. 47 Ω
  3. 4.7 Ω
  4. 0.47 Ω
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Answer: C. 4.7 Ω

R marks the decimal point: 4.7 Ω.

Question 4Why are resistor values like 10, 12, 15, 18, 22 ... and not 10, 20, 30 ...?

  1. Tradition only
  2. They are spaced by a constant ratio so each value's tolerance band meets the next
  3. They are easier to make
  4. Prime numbers resist better
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Answer: B. They are spaced by a constant ratio so each value's tolerance band meets the next

Geometric spacing: about 21 % per step for E12.

Question 5What is the highest value of a 2.2 kΩ ±10 % resistor?

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Answer: 2420 Ω

2200 × 1.1 = 2420 Ω.

Question 6Which is the usual through-hole resistor in modern designs?

  1. Carbon composition
  2. 1 % metal film
  3. Wirewound
  4. Ceramic cement
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Answer: B. 1 % metal film

Metal film: precise, stable and low noise.

Question 7Two 4.7 kΩ resistors in parallel, in series with 2.2 kΩ, make:

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Answer: 4550 Ω

4.7 k / 2 = 2.35 k; + 2.2 k = 4.55 kΩ.