If an electrical instrument is dissipating 100 W of energy when a current of 10 A is passingthrough it, then the resistance of the instrument will be
Correct answer: A. 1 Ω.
- A. 1 Ω.
- B. 10 Ω.
- C. 100 Ω.
- D. 1000 Ω.
Explanation
To determine the resistance of the electrical instrument, use the formula for power dissipation in terms of current and resistance: P = I2 * R. Rearrange the formula to solve for resistance: R = P / I2. Given that the power P is 100 W and the current I is 10 A, substitute these into the formula: R = 100 W / (10 A)2 = 100 W / 100 A2 = 1 Ω. Therefore, the correct answer is 1 Ω.The other options provide incorrect values because they do not correctly apply the formula for calculating resistance based on the given power and current values.
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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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