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Which of the following is a safety device used to prevent excessive current from flowing in electrical circuits?
Capacitor
Resistor
Fuse
Transformer
Fuse
A fuse is a safety device designed to protect electrical circuits from damage caused by excessive current. It consists of a thin metallic wire with a low melting point that melts and breaks the circuit when current exceeds a predetermined threshold.
A fuse is a safety device designed to protect electrical circuits from damage caused by excessive current. It consists of a thin metallic wire with a low melting point that melts and breaks the circuit when current exceeds a predetermined threshold.
Think of a fuse like a 'sacrificial bridge' that collapses on purpose when too much traffic tries to cross at once, stopping any more vehicles from reaching the other side and potentially causing a bigger disaster.
F-M-B: Fuse Melts, Breaks-circuit.
H=I2Rt тАФ Joule's Law of heating where I is current, R is resistance, and t is time.
P=VI тАФ Relationship between Power, Voltage, and Current.
The fuse operates on the heating effect of electric current, defined by Joule's Law: H=I2Rt. When the current (I) exceeds the safe limit, the heat generated (H) causes the fuse wire to reach its melting point quickly and melt (fuse), creating an open circuit that stops the flow of electricity.
A fuse is always connected in series with the live wire.
The fuse wire is typically made of an alloy of Lead and Tin (solder) or Copper, known for low melting points.
A fuse rating is expressed in Amperes (A).
It acts as a preventive measure against short circuits and overloading.
Cheap and simple construction
Provides reliable protection against overload
No maintenance required
Requires manual replacement once blown
Not reusable compared to modern Circuit Breakers (MCBs)
Domestic wiring circuits
Automotive electrical systems
Electronic appliance internal circuits
Option A (Capacitor) stores electrical energy in an electric field.
Option B (Resistor) restricts or reduces current flow but does not break the circuit during overloads.
Option D (Transformer) is used to step up or step down AC voltage levels.
C is correct тАФ A fuse serves as a sacrificial safety device that interrupts the circuit by melting when excessive current flows through it.
Always remember that fuses are connected in series, not parallel, because the entire current must pass through the fuse for it to monitor the load effectively.
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