When the short circuit condition occurs, the current in the circuit
- A.becomes zero
- B.remains constant
- C.increases substantially
- D.keeps on changing randomly
Correct answer
Explanation
The correct answer is C, increases substantially. In a short circuit the resistance of the path falls almost to zero, so by Ohm's law the current rises sharply.
A short circuit happens when the live wire and the neutral wire touch directly, often because the insulation is damaged or an appliance is faulty. The current then bypasses the load and flows through a path of very low resistance. Since current equals voltage divided by resistance (I = V/R), a tiny resistance at the same mains voltage gives a very large current. This heats the wires and can cause sparks or fire, which is why circuits carry a fuse or an MCB that breaks the circuit when the current becomes too high.
A is wrong because zero current is what happens in an open circuit, when the path is broken. B is wrong because the current cannot stay the same once the resistance drops sharply. D is wrong because the change is a sudden steep rise, not a random fluctuation.
Exam tip: Short circuit means resistance near zero and current very high; open circuit means no current.
Practice Questions
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- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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- B.Objective lens-Condenser-Body tube-Eyepiece
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- D.Eyepiece-Objective lens-Body tube-Mirror
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- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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