T2 CH2 Electricity - Tamil Nadu Board STD 7 Science Questions

Q 1MCQ1 Mark

Study the three electric circuits below. Each of them has a glass rod (G), a steel rod (S), and a wooden rod (W)
In which of the electric circuits would the bulb not light up.

A
A only
B
C only
✓
A and B only
D
A , B and C

Answer: C.

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Q 2MCQ1 Mark

Study the electric circuit below. Which of the following switches should be closed so that only two bulbs will light up

A
S1,S2 and S4 only
B
S1, S3 and S5 only
✓
S2, S3 and S4 ony
D
S2, S3 and S5 only

Answer: C.

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Q 3MCQ1 Mark

Picture based Question
Three conductors are joined as shown in the diagram
The current in conductor RS is 10 A. The current in conductor QR is 6 A. What will be the current in conductor P

✓
4 A
B
6:A
C
10A
D
16A

Answer: A.

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Q 4MCQ1 Mark

In which of the following circuits are the bulb connected in series?

Answer: B.

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Q 5MCQ1 Mark

Small amounts of electrical current are measured in milliampere (mA). How many milliampere are there in 0.25 A ?

A
2.5 mA
B
25 mA
✓
250 mA
D
2500 mA

Answer: C.

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Q 6Fill in the blanks.1 Mark

milli ampere: micro ampere : : 10-3A : ______.

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Q 7Fill in the blanks.1 Mark

Length: metre scale: : Current: ______

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Q 8Fill in the blanks.1 Mark

Copper: conductor:: Wood: ______.

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Q 9Fill in the blanks.1 Mark

Water : pipe :: Electric current : ______.

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Q 10Fill in the blanks.1 Mark

S.I. unit of Electrical conductivity of a conductor is ______.

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Q 11Assertion & Reason1 Mark

Assertion (A): Insulators do not allow the flow of current through themselves.
Reason (R): They have no free charge carriers.

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Q 12Assertion & Reason1 Mark

Assertion (A): Copper is used to make electric wires.
Reason (R): Copper has very low electrical resistance.

✓
Both A and R are true and R is the correct explanation of A.
B
Both A and R are true but R is NOT the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer: A.

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Q 13Assertion & Reason1 Mark

Assertion (A) : The connecting wires are made of copper.
Reason (R) : The electrical conductivity of copper is high.

✓
Both A and R are true but R is the correct explanation of A.
B
Both A and R are true and R is the not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer: A.

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Q 14Assertion & Reason1 Mark

Assertion (A) : A current carrying wire should be charged.
Reason (R) : The current in a wire is due to flow of free electrons in a definite direction.

A
Both A and R are true but R is the correct explanation of A.
B
Both A and R are true and R is the not the correct explanation of A.
C
A is true but R is false.
✓
A is false but R is true.

Answer: D.

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Q 15Assertion & Reason1 Mark

Assertion (A) : Insulators do not allow flow of current through them.
Reason (R) : Insulators have no free charge carrier.

✓
Both A and R are true but R is the correct explanation of A.
B
Both A and R are true and R is the not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer: A.

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Q 16TRUE & FALSE1 Mark

The electrical conductivity of the semiconductor is in between a conductor and an insulator.

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Q 17TRUE & FALSE1 Mark

The representation of the electric current is A

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Q 18TRUE & FALSE1 Mark

In a parallel circuit, the electric components are divided into branches.

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Q 19TRUE & FALSE1 Mark

The fuse wire does not melts whenever there is overload in the wiring.

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Q 20TRUE & FALSE1 Mark

Electron flow is in the same direction to conventional current flow.

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Q 21Answer In One word.1 Mark

Define electrical conductivity.

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Q 22Answer In One word.1 Mark

Define an electric current.

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Q 23Answer In One word.1 Mark

What is a battery?

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Q 24Answer In One word.1 Mark

Name few insulators.

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Q 25Answer In One word.1 Mark

Name some devices that run using heat effect of electric current

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Q 26[ 2 Marks Questions ]2 Marks

Higher Order Question
A student made a circuit by using an electric cell, a switch, a torch bulb (fitted in the bulb holder), and copper connecting wires. When he turned on the switch, the torch bulb did not glow at all. The student checked the circuit and found that all the wire connections were tight.

What could be the possible reason for the torch bulb not glowing even when the circuit appears to be complete?

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Q 27[ 2 Marks Questions ]2 Marks

Observe the circuit given:
1.Would any of the bulb glow when the switch is in the ‘OFF’ position?

2.What will be the order in which the bulbs A, B and C will glow when the switch is moved to the ‘ON’ position?

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Q 28[ 2 Marks Questions ]2 Marks

What is the difference between fuse wire and a heating wire?

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Q 29[ 2 Marks Questions ]2 Marks

If $3A$ current flows through a circuit, then convert the current in terms of milliampere.

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Q 30[ 2 Marks Questions ]2 Marks

If $5A$ current flows through a circuit, then convert the current is terms of micro ampere?

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Q 31Match The Following5 Marks

Match the following

1.	Cell	used to open or close a circuit
2.	Switch	safety device used in electric circuit
3.	Circuit	A complete path for the flow of an electric current
4.	Miniature circuit Breaker	Reset by hand, circuit becomes complete once again
5.	Fuse	A device which converts chemical energy into electrical energy