Electricity

71.	A fuse wire is used for…..
	A. Pass high current without causing harm
	B. Breaking the electric circuit at the time of excessive current flow
	C. Protect a person from electric shock
	D. None of these Option”B” is correct. Fuse wire is used in electric circuits to prevent the excess current flowing into the circuit and therefore preventing the appliances from getting damaged.

72.	The safety fuse wire used in domestic electrical appliances is made of a metal whose
	A. Reduce resistance
	B. Low melting point
	C. Have a low specific gravity
	D. Have low conductivity Option”B” is correct. Fuse is an essential component is a metal wire or strip that melts when too much current flows through it, thereby stopping or interrupting the current. It is a sacrificial device; once a fuse has operated it is an open circuit, it must be replaced or rewired, depending on type. So fuse wires are made up of materials with lower melting points so that as soon as higher currents are passed, it gets heated up and break by melting thus breaking the circuit The commonly used fuse wire is made of an alloy of tin and lead.

73.	The substance used in electric fuse is an alloy of tin and lead__
	A. Should have high specific resistance and low melting point
	B. Should have low specific resistance and high melting point
	C. Should have low specific resistance and low melting point
	D. Should have high specific resistance and high melting point Option”C” is correct

74.	In the power supply, the fuse is fitted in the mains as a safety device, which statement is correct regarding the fuse in the power supply?
	A. It is connected in parallel with the mains switch
	B. It is mainly composed of silver alloys.
	C. Its melting point is low
	D. Its resistance is very high Option”C” is correct

75.	A fuse wire is used in an electrical circuit
	A. To reduce the cost of electrical energy in transmission
	B. To keep the voltage level constant
	C. To stop excess current flowing in a circuit
	D. To avoid overheating of electric wire Option “C” is correct

76.	The principle of fuse is__
	A. Chemical effect of electric current
	B. Mechanical effects of electric current
	C. Heating effect of electric current
	D. Electromagnetic effect Option “C” is correct. Electric fuse works on the principle of the heating effect of electric current. It is placed in series with the device. A fuse consists of a piece of wire made of a metal or an alloy of an appropriate melting point, for example, aluminum, copper, iron, lead etc.

77.	What is fuse wire made of?
	A. Tin and copper alloys
	B. Mixture
	C. Tin and aluminum alloys
	D. Nickel-chromium alloy Option “A” is correct. Due to their high resistance and low melting point, tin and lead are combined to form the fuse wire. The composition of the tin and lead alloy, which melts at 183 ° C , is tin and lead.

78.	Which of the following set of properties is essential for an electric fuse wire for normal applications?
	A. Thick wire, high melting point alloy, short length
	B. Thicker wire low melting point alloy longer length
	C. Short length low melting point alloy thin wire
	D. Long, low melting point alloy, thin wire Option “C” is correct

79.	Name the element used as filament in electric bulb?
	A. Copper
	B. Iron
	C. Leads
	D. Tungsten Option “D” is correct

80.	There is a loud sound on breaking the bulb because-
	A. The air outside rushes to fill the vacuum inside the bulb.
	B. There is an explosive gas inside the bulb
	C. The filament of the bulb reacts with the air
	D. The gas inside the bulb suddenly circulates Option “A” is correct. High vacuum is used to create a bulb, so when that bulb explodes then the air which is present outside to the bulb rushes to fill the gap, due to which the sound generates.

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