CRAC Class B (2025) — Questions 961–970
U1036. Surface-mount devices (SMDs) are widely used in amateur radio projects. The size codes 0402, 0603, 0805, 1206 etc. refer to:
表面贴装元器件（surface-mount devices）广泛应用于业余 无线电作品。其规格参数0402、0603、0805、1206等是 指：
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SMD package codes (e.g., 0805) denote the body length × width — in inches as hundredths (08×05 → 0.08"×0.05") or equivalently in mm. They are not the component value. Option A is correct.
U1037. A resistor's color bands are, in order, brown, orange, orange, black. Its resistance is:
某电阻上的色环依次为棕、橙、橙、黑。其阻值为：
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Four-band code: brown(1) = 1st digit, orange(3) = 2nd digit, orange = multiplier ×10³, black = ±20% tolerance. Value = 13 × 10³ = 13 kΩ. Option A is correct.
U1038. A resistor's color bands are, in order, yellow, white, red, silver. Its resistance is:
某电阻上的色环依次为黄、白、红、银。其阻值为：
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Four-band: yellow(4) = 1st digit, white(9) = 2nd digit, red = multiplier ×10², silver = ±10% tolerance. Value = 49 × 100 = 4.9 kΩ. Option A is correct.
U1039. A resistor's color bands are, in order, silver, black, orange, orange, brown. Its resistance is:
某电阻上的色环依次为银、黑、橙、橙、棕。其阻值为：
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This is a five-band code; the brown band at the right is the ±1% tolerance band, and the special silver first band marks a low- value resistor. Decoded, the significant figures and multiplier give 133 Ω. The other options (13 kΩ, 4.7 MΩ, 130 kΩ) do not match the bands.
U1040. A chip resistor is marked "2R7". Its resistance is:
某贴片电阻上的印字为2R7。其阻值为：
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On SMD resistors the letter R stands for the decimal point, so "2R7" = 2.7 Ω. Option A is correct. B/C misplace the point; D confuses it with a network.
U1041. A chip resistor is marked "3802". Its resistance is:
某贴片电阻上的印字为3802。其阻值为：
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A four-digit SMD code uses the first three digits as the value and the last as the power-of-ten multiplier: "3802" = 380 × 10² = 38,000 Ω = 38.0 kΩ. Option A is correct.
U1042. When building circuits with higher operating voltages, one should pay attention to component voltage ratings to improve safety. To ensure the voltage rating of the resistors used, useful experience includes: (Choose all that apply.)
制作工作电压较高的电路应当关注元器件的耐压。这可以提高 电路的安全性。要确保所用电阻的耐压，可供借鉴的经验有：
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To raise a resistor's effective voltage rating you can (A) choose higher-rated parts or larger packages, and (B) series-connect resistors so the voltage divides among them. Parallel connection (D) shares current, not voltage, and does not raise the voltage rating; simply preferring metal-film over carbon (C) does not guarantee a higher rating. So A and B are correct.
U1043. A potentiometer is a three-terminal resistive element whose contact end slides on the resistive body. It can be used in a circuit as: (Choose all that apply.)
电位器是一种触点端与电阻体滑动接触的三端电阻元件。其在 电路中可以用作：
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A potentiometer (电位器) uses all three terminals as an adjustable voltage divider (A), or two terminals as a variable resistor (B, rheostat). It is not a transformer (C) or a reactance element (D). So A and B are correct.
U1044. Which of the following components can be used to implement volume adjustment?
以下哪种元件可以用来实现音量调节功能？
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Volume control is implemented with a potentiometer acting as an adjustable attenuator/divider (电位器). A transformer, modulator, or demodulator does not set audio level. Option A is correct.
U1045. A capacitor is formed by two electrodes insulated from each other. If subdivided by manufacturing material, common capacitors include: (Choose all that apply.)
电容器由彼此绝缘的两个电极构成。若按制造材料细分，常见 电容器包括：
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A 电容器 (capacitor) consists of two insulated electrodes; by material, the common discrete types are ceramic (陶瓷电容), electrolytic (电解电容), and organic-film (有机薄膜电容) capacitors. "线间电容" (inter-winding or wiring capacitance) is an unwanted stray/parasitic effect, not a discrete manufactured capacitor type, so D is excluded.