The unknown resistance of the given Whetstone bridge is
Correct answer: D. 40 Ω.
- A. 2.5 Ω.
- B. 5 Ω.
- C. 20 Ω.
- D. 40 Ω.
Explanation
5 / 20 = 10 / R4To find R4, we can cross-multiply:5 * R4 = 20 * 105 * R4 = 200R4 = 200 / 5R4 = 40 ΩTherefore, the unknown resistance R4 is 40 Ω.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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