Electric Circuit Diagram

Q.

What will happen if you directly join the two terminals of a cell without connecting them to a switch or a bulb? [1 MARK]

Q.

What will happen if you use an uninsulated copper wire for making an electromagnet?

Q.

Question 16

Why do bulbs have two terminals?

Q.

The 'symbols' in a circuit diagram represent the components of the electric circuit.

1. False

2. True

Q. The bulb in the circuit shown in figure does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow. [3 MARKS]

Q.

The brightness of light emitted by a bulb is observed to decrease when an electric heater is connected in series with it .Suggest the likely reason for this observation

Q. Two metallic wires A and B are connected in series. Wire A has length L and radius r, while B has length 2L and radius 2r. Find the ratio of the total resistance of series combination.

Q. In which of the following circuits the bulb will glow?

1. C
2. B
3. A
4. D

Q.

In a circuit with one bulb, another bulb is added in series. What happens to the bulbs when current is passed?

1. They do not glow.

2. They glow less brightly.

3. They glow more brightly.

4. They get fused.

Q. An incandescent lamp was connected to an electric circuit but it did not glow. Which of the following could not be a valid reason for the bulb not glowing?

1. The switch in the circuit was not closed.
2. The filament of the bulb was burnt out.
3. The positive and negative terminals of the battery were interchanged.
4. The battery was out of power.

Q.

A current flows through an open circuit.

Say True or False.

1. True

2. False

Q.

Why should we not touch a lighted bulb? Which phenomenon is responsible for it? [2 MARKS]

Q. Question 1

Which of the following effects can be produced by electric current? Illustrate with examples.
(a) heating effect only.
(b) chemical effect only.
(c) magnetic effect only.

Q.

Imagine your friend made the following circuit for an experiment, out of curiosity:

If he connects both the wires to a single terminal of the bulb, the bulb starts glowing as soon as the wires are connected to the cell.

1. True

2. False

Q. Name one necessary component of an electric circuit.

Q. Match the following electrical symbols with the names of their components.

1. Closed switch
2. Bulb
3. Battery

Q.

When the switch of an electric torch is in ON position, electric current flows to the filament of the electric bulb due to which it ___.

1. gets cooled

2. does not glow

3. gets heated

4. glows

Q.

Which of the following represents correct symbol for an electric bulb?

1. 

2. 

3. 

4. 

Q.

To make the bulb glow, it is advisable___

1. to connect one terminal of the battery to one terminal of the bulb, and keeping other terminals open.

2. to connect the terminals of the bulb to one of the terminals of the battery.

3. to connect the terminals of the battery to only one terminal of the bulb.

4. to connect the terminals of the battery to two different terminals of the bulb.

Q.

What does the above symbol represent?

1. Resistance

2. Battery

3. Bulb

4. Fan

Q.

An incandescent bulb works on which of the following principles:

1. Magnetic effect of electric current

2. Heating effect of electric current

3. Both A and B

4. Chemical effect of electric current

Q.

Why do we use a short wire in fuse and not long wire if we know that more is the length more is the heat produced

Q.

While connecting a bulb to a battery, one of the terminals of the battery was left disconnected. Pick the correct statement.

1. Brightness of the bulb would decrease

2. Bulb would not glow

3. None of these

4. Brightness of the bulb would increase

Q.

The wire having a green plastic covering is a

1. live wire

2. neutral wire

3. earth wire

4. none of these

Q. Choose the correct battery representation (from the end X to the end Y) for the circuit in which three bulbs A, B and C are connected as shown.

1. 

2. 

3. 

4. 

Q.

Which of the following is true for a multistranded wire?

1. The increased surface area of multi-stranded wire decreases the amount of resistance.

2. The increased surface area of multi-stranded wire increases the amount of resistance.

3. The decreased surface area of the multi-stranded wire decreases the amount of resistance

4. The decreased surface area of multi-stranded wire makes the amount of resistance almost nil.

Q.

How MCBs prevent the damage of household electric items?

1. By breaking the circuit, thus stopping the current

2. By increasing the current in the circuit

3. By keeping the current in the circuit constant

4. By decreasing the current in the circuit

Q.

An electric current causes:

1. Heating effect in a conductor

2. Magnetic field around a conductor

3. Light production from the conductor

4. Cooling effect in a conductor

Q.

How do we connect these two identical cells of 1.5 volt each to design a 3.0 volt battery?

1. Connect terminal A to D.

2. Connect terminal D to B.

3. Connect terminal B to C.

4. Connect terminal A to C.

Q. When the switch of an electric torch is in ON position, the electric current flows from the electric cell to the filament of an electric bulb due to which it:

1. gets cooled

2. does not glow

3. gets heated

4. glows