Class 6 Science Chapter 9 Practice Question Answers - Electricity and Circuits

Q1: Choose the correct option: A battery consists of
(a) a single cell a combination of cells in which cells are joined (+) to (+)
(b) a combination of cells in which cells are joined (+) to (-)
(c) a combination of cells in which cells are joined (+) to (+)
(d) None of the above
Ans: (b)
Two or more cells are combined in such a way that the  (+) terminal of one cell is joined to the (-) terminal of the other is called battery.

Q2: Choose the correct option: Substances which allow electricity to pass through it are called
(a) an insulator
(b) a conductor
(c) superconductor
(d) semiconductor
Ans: (b)
Substances allow an electric current to pass through them.

Q3: Choose the correct option: Which is an example of an insulator
(a) bakelite
(b) aluminium
(c) tap water
(d) All of these
Ans: (a)
Aluminium and tap water are conductors of electricity.

Q4: Choose the correct option: An example of a conductor is
(a) tap water
(b) salt solution
(c) metal wire
(d) all of these
Ans: (d)
Tap water, salt solution and metal wire are examples of conductors.

Q5: Choose the correct option: How many terminals are present in a dry cell?
(a) One
(b) Two
(c) Three
(d) Four
Ans: (b)
A dry cell has two terminals (+ve) and (-ve).

Q6: Choose the correct option: To prevent electric shocks, the metallic electrical wires are insulated with
(a) paper
(b) aluminium
(c) cotton
(d) plastic
Ans: (d)
Plastic is an insulator of electricity.

Q7: What is the purpose of using an electric switch? Name some of the electrical gadgets that have switches built into them.
Ans: The function of a key in an electric circuit is to complete the circuit or break the circuit. All the electric gadgets have switches built into them like television, oven, fan etc.

Q8: What is fuse? How does it work?
Ans: A fuse is attached to an electric circuit in order to prevent excess flow of current throughout the circuit. Fuse is an electrical object which is made by materials of specific resistance. If high voltage current flows through the circuit, then due to high temperature and heat generated the fuse melts therefore breaking the circuit. Fuse is attached in circuits of households or places with electric connection. This saves other electronic devices from being damaged in short circuits.

Q9: What is an electric circuit?
Ans: Electric circuit consists of a wire, battery, switch, and appliance. An electric circuit is defined as a closed path through which electricity passes. through the positive terminal of the battery to the negative terminal. The switch is used to break or start the flow of electricity in a circuit made from a conductive substance.

Q10: How does the bulb function, and what causes the bulb to fuse?
Ans: A bulb is an electric appliance which emits light by converting electric energy into light energy.
A bulb consists of a thin wire-like structure known as a filament. When the circuit is switched on, electricity passes through the electric current. This causes the filament present in the bulb to heat up, and the bulb is lit up.
The filament is usually made by substances having high melting points, as when electricity passes the filament, it lights up and gets heated. But sometimes, when there is a surge of electricity in the circuit, more amount of electricity passes through the filament causing the filament to heat up more hence increasing its temperature. This causes the filament to melt due to excessive heat. This results in the fusing of the bulb.

Q11: Paheli wanted to glow a torch bulb using a cell. She could not get connecting wires; instead, she got two strips of aluminium foil. Will she succeed? Explain how?
Ans: Paheli will succeed in glowing a torch bulb using aluminium foil as aluminium is a metal; hence it conducts electricity. By attaching one strip of aluminium to the positive terminal of the bulb and the other to the negative terminal of the bulb, the circuit will be completed, and electricity will pass through, resulting in the torch bulb glowing.

Q12: Define
(i) Electric cell
(ii) Battery
Ans: (i) Electric cell is the source of energy in an electric circuit. It produces electricity through chemical reactions present inside the cell.
(ii) Battery is formed when two or more cells are joined together in a circuit.

Q13: Why should an electrician use rubber gloves while repairing an electric switch at your home? Explain.
Ans: An electrician uses rubber gloves while repairing an electric switch at your home as rubber is an insulator and hence will not allow electricity to pass through it. Hence using rubber gloves protects the electrician from electric shock.

Q14: What are the reasons why the bulb in an electric circuit does not light up?
Ans: Given below are some of the reasons why a bulb does not light up in an electric circuit:

• Only one of the wires is connected properly to the electric cell, while the other is poorly connected or not connected at all.
• Two different wires are not connected or soldered properly.
• One wire is connected properly to the bulb, while the other is not connected or is poorly connected.

Q15: What is the purpose of using an electric switch? Name some of the electrical gadgets that have switches built into them.
Ans: The function of a key in an electric circuit is to complete the circuit or break the circuit. All the electric gadgets have switches built into them like television, oven, fan etc.