Fuses prevent electrical overloads by breaking circuits

Steps:

• Identify the function of a fuse: it contains a thin wire that melts under excessive current.
• Understand overload risks: high current can overheat and damage appliance components or cause fires.
• Recognize protection mechanism: melting wire interrupts the circuit, stopping current flow.
• Confirm purpose: this safeguards the appliance without altering power or voltage.

Why B is correct:

• A fuse protects the appliance by melting its wire when current exceeds the rated value, breaking the circuit per Ohm's law (I = V/R) to prevent overheating and damage.

Why the others are wrong:

• A: Earthing grounds excess charge to prevent shocks, not the fuse's role.
• C: Fuses do not adjust power output; they only interrupt flow during faults.
• D: Voltage regulation uses transformers, not fuses, which maintain supplied voltage until they blow.

Final answer: B