In a domestic electric circuit, the fuse is connected
- A.in the neutral wire
- B.in the live wire
- C.in the earth wire
- D.in parallel with the appliance
Correct answer
Explanation
The correct answer is B, in the live wire. The fuse is a short piece of wire of low melting point placed in series in the live line, so that an excessive current melts it and breaks the circuit. Because the break is made on the live side, the appliance is left completely disconnected from the high potential and is safe to handle.
Option A is wrong because a fuse in the neutral wire would indeed stop the current, but the appliance would remain joined to the live wire and anyone touching it could still receive a shock. Option C is wrong because the earth wire is a safety path to the ground and must never carry a fuse, as breaking it would remove the very protection it provides. Option D is wrong because a fuse placed in parallel would short the appliance instead of protecting it; a fuse is always in series with the load it protects.
Read the full article: Electricity and Magnetism: Laws, Rules and PYQs
Practice Questions
View allIf the potential difference across the ends of a conductor is halved, what happens to the current flowing through it?
- A.It gets increased
- B.It gets doubled
- C.It gets decreased
- D.It gets halved
Show answer
By Ohm's law, at a constant temperature the current through a conductor is directly proportional to the potential difference across its ends, since the current equals the potential difference divided by the resistance.
Read the full explanation →What is the work done to move a unit charge from one point to another in an electric circuit carrying some current, between those two points?
- A.Pressure distance
- B.Potential difference
- C.Potential distance
- D.Pressure difference
Show answer
The potential difference between two points in a circuit is defined as the work done in moving a unit positive charge from one point to the other.
Read the full explanation →Which of the following is NOT based on the heating effect of current?
- A.Electric heater
- B.Electric bulb (with filament)
- C.Electric iron
- D.Microwave
Show answer
A microwave oven does not cook by passing a current through a resistance. It generates microwaves in a magnetron, and these waves make the water molecules in the food rotate rapidly, so the food heats from within by dielectric heating.
Read the full explanation →A 12 V battery is connected across an unknown resistor. If a current of 2 mA is flowing through the circuit, the value of the resistance is _________ .
- A.600 ohm
- B.6 ohm
- C.6000 ohm
- D.60 ohm
Show answer
By Ohm's law the resistance equals the potential difference divided by the current. Here the current must first be converted into the base unit: two milliampere is 0.002 ampere.
Read the full explanation →Thin wires of which of the following metal is used for making the filament of electric bulbs?
- A.Tungsten
- B.Silver
- C.Nichrome
- D.Copper
Show answer
Tungsten has the highest melting point of all metals, well above three thousand degrees Celsius, so a thin tungsten wire can be heated until it glows white without melting.
Read the full explanation →