Four 20 Ω resistors are connected in parallel and combination is connected to a 20 V emf device. The current in the device is:
Correct answer: C. 4.0 A
- A. 0.25 A
- B. 1.0 A
- C. 4.0 A
- D. 5.0 A
Explanation
Parallel Resistance is calculated by 1/Rt= (1/R1 + 1/R2 ...) hence Rt = 5Ohm. EMF is 20, and Ohm's Law, V=IR, determines I (current) as 4.0A
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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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