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Question (21)

QN001901

Overheating in electrical appliances may lead to

(A) melting of plastic parts
(B) freezing of wires
(C) permanent cooling
(D) stopping of resistance

Correct Answer: A

Explanation:

Excessive heating can melt plastic parts.

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Question (22)

QN001902

Why are safety devices used in household circuits?

(A) To decorate switchboards
(B) To minimise damage due to overheating
(C) To produce stronger magnetic fields
(D) To increase current continuously

Correct Answer: B

Explanation:

Safety devices help prevent damage due to overheating.

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Question (23)

QN001903

An electric stove and a charcoal stove are compared. The electric stove is considered more convenient mainly because it

(A) produces smoke continuously
(B) works cleanly and quickly
(C) requires burning wood
(D) needs no electricity

Correct Answer: B

Explanation:

Electric stoves are cleaner and more convenient.

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Question (24)

QN001904

Which industrial application uses heating effect of electric current?

(A) Compass manufacturing only
(B) Electric furnace for melting steel
(C) Water purification only
(D) Bar magnet production only

Correct Answer: B

Explanation:

Electric furnaces use heating effect to melt steel.

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Question (25)

QN001905

In steel manufacturing industries, electric current is used to

(A) cool iron rapidly
(B) generate magnetic poles only
(C) produce heat for melting scrap steel
(D) stop flow of electricity

Correct Answer: C

Explanation:

Electric current produces heat for melting and recycling steel.

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Question (26)

QN001906

A heating wire remains cool when the switch is OFF because

(A) resistance becomes zero
(B) no current flows through the wire
(C) wire becomes non-metallic
(D) magnetic poles disappear

Correct Answer: B

Explanation:

Heating occurs only when current flows.

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Question (27)

QN001907

Which statement correctly explains the heating effect of electric current?

(A) Current changes heat energy into electrical energy
(B) Electrical energy changes into heat energy
(C) Heat energy changes into magnetic energy only
(D) Current destroys electrical energy completely

Correct Answer: B

Explanation:

Heating effect converts electrical energy into heat energy.

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Question (28)

QN001908

A student uses a copper wire instead of nichrome wire in the heating activity. Compared to nichrome, the copper wire will generally

(A) heat more quickly
(B) produce less heat
(C) become non-conducting
(D) melt instantly

Correct Answer: B

Explanation:

Copper has lower resistance than nichrome.

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Question (29)

QN001909

Why should appropriate plugs and sockets be used in household wiring?

(A) To increase brightness only
(B) To avoid unnecessary heating and fire risk
(C) To increase wire resistance greatly
(D) To stop current flow completely

Correct Answer: B

Explanation:

Proper plugs and sockets reduce overheating and fire hazards.

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Question (30)

QN001910

Which of the following is an example of useful heating effect of electric current?

(A) Melting of switchboard plastic
(B) Fire due to short circuit
(C) Heating water using immersion rod
(D) Overheating of loose connections

Correct Answer: C

Explanation:

Immersion rods use heating effect to heat water.

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Question (21)

Overheating in electrical appliances may lead to

Explanation:

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Question (22)

Why are safety devices used in household circuits?

Explanation:

Link:

Question (23)

An electric stove and a charcoal stove are compared. The electric stove is considered more convenient mainly because it

Explanation:

Link:

Question (24)

Which industrial application uses heating effect of electric current?

Explanation:

Link:

Question (25)

In steel manufacturing industries, electric current is used to

Explanation:

Link:

Question (26)

A heating wire remains cool when the switch is OFF because

Explanation:

Link:

Question (27)

Which statement correctly explains the heating effect of electric current?

Explanation:

Link:

Question (28)

A student uses a copper wire instead of nichrome wire in the heating activity. Compared to nichrome, the copper wire will generally

Explanation:

Link:

Question (29)

Why should appropriate plugs and sockets be used in household wiring?

Explanation:

Link:

Question (30)

Which of the following is an example of useful heating effect of electric current?

Explanation:

Link:

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