Electric Bulb and Electric Fuse

Q.

Question 3

Three bulbs A, B, C are connected in a circuit as shown in Figure. When the switch is ‘ON’

(a) bulb C will glow first

(b) bulb B and C will glow simultaneously and bulb A will glow after some time

(c) all the bulbs A, B and C will glow at the same time

(d) the bulbs will glow in the order A, B and C

Q.

Question 6

Which property of a conducting wire is utilized in making electric fuse?

Q.

The topology with highest reliability.

Q.

Question 8 (d)
The safety device based on the heating effect of electric current is called a ___.

Q. Which substance is used to make the filament of bulb?

1. Tungsten
2. Aluminium
3. Mercury
4. Copper

Q.

Which wire has a red insulation in an electrical wiring?

1. Neutral wire

2. Earth wire

3. Fuse wire

4. Live wire

Q.

What are the various reasons for excessive current in electric circuits? What can we do to prevent them? [3 MARKS]

Q.

What is the terminal potential difference of a cell when short-circuited?

Q.

Can I use a $440V$ capacitor instead of a $370V$

Q.

Question 11
An electrician is carrying out some repairs in your house. He wants to replace a fuse with a piece of wire. Would you agree? Give reasons for your response.

Q. Electric wires that melts quickly and breaks when large amount of current is applied are known as

1. Bulbs
2. Electric fuses
3. Electric cells
4. Batteries

Q. If the filament of a bulb is broken, then the bulb is said to be ___.

1. brightened
2. dimmed
3. fused
4. restrained

Q.

Question 9 (b)
Mark ‘T’ if the statement is true and ‘F’ if it is false:
When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks.

Q. What does a 5 A rating on a fuse mean?

1. Fuse melts down if the current is less than 5 A.
2. Fuse allows a current only equal to 5 A through it.
3. Fuse produces energy if current is less than 5 A.
4. Fuse melts if the current is more than 5 A.

Q.

Select the most appropriate option:

Statement 1: During a short circuit, two wires come in contact without the presence of resistance in between and a large amount of current flows through the circuit.

Statement 2: In case of overloading many devices are connected to the same circuit and hence a low current flows through the circuit.

1. Both statements are correct

2. Statement 1 is correct and statement 2 is incorrect

3. Statement 1 is incorrect and statement 2 is correct

4. Both statements are incorrect

Q.

15. Name the scientist who discovered the following.

(c) Safety lamp

Q.

Question 2

Choose the statement which is not correct in the case of an electric fuse.

(a) Fuses are inserted in electric circuits of all buildings

(b) There is a maximum limit on the current which can safely flow through the electric circuits

(c) There is a minimum limit on the current which can safely flow in the electric circuits

(d) If a proper fuse is inserted in a circuit it will blow off if current exceeds the safe limit

Q.

Assertion(A): All the bulbs connected in parallel glow brightly

Reason(R): All the bulbs are connected directly to a battery and derive the required electrical energy.

1. Both (A) and (R) are correct and (R) is the correct explanation for (A)

2. Both (A) and (R) are correct but (R) is not the correct explanation for (A)

3. (A) is correct but (R) is not correct

4. (A) is not correct but (R) is correct

Q.

Why do short circuit take place, if more current is made to flow through this wire?

Q. Can we fuse an iron wire in a glass rod? Give reason to your answer.

Q. In a household electric circuit:

1. all electric appliances drawing power are joined in parallel
2. a switch may be either in series or in parallel with the appliance which it controls
3. if a switch is in parallel with an appliance, it will draw power when the switch in the off position (open)
4. if a switch is in parallel with an appliance, the fuse will blow (burn out) when the switch is put on (closed)

Q.

The connecting wires are generally at a higher temperature as compared to the filament of a bulb.

1. False

2. True

Q.

Question 12

Why is an electric fuse required in all electrical appliances?

Q.

_________ is the safety device does not have to be changed when excess current flows through it.

Q. What is a miniature circuit breaker?

Q.

An electric bulb works on which of the following principles:

1. Both A and B

2. Magnetic effect of electric current

3. Heating effect of electric current

4. Chemical effect of electric current

Q. Which property of a conducting wire is utilised in making electric fuse?

Q. What does a 5 A rating on a fuse mean?

1. Fuse melts down if the current is less than 5 A.
2. Fuse produces energy if current is less than 5 A.
3. Fuse allows a current only equal to 5 A through it.
4. Fuse melts if the current is more than 5 A.

Q. Why is a fuse wire made of a tin-lead alloy and not copper?

Q. What is a fuse wire? What is the advantage and disadvantage of using a thick fuse wire?