Science - Electricity and Circuits
Exam Duration: 45 Mins Total Questions : 30
Most of the electricity-carrying wires along the roads do not have a plastic covering like the wires used at homes. But why is there no substantial loss of energy?
- (a)
Air is not affected by gravity.
- (b)
Air is a bad conductor of electricity.
- (c)
Electricity flows very fast near highways.
- (d)
Current rating is high near highways
Electric heaters used for cooking have a filament or a heating coil placed on a plate made up of clay. Why is this so?
(i) It is a bad conductor of heat.
(ii) It is a bad conductor of electricity.
(iii) It is porous.
- (a)
Only (i) and (ii)
- (b)
Only (ii) and (iii)
- (c)
Only (i) and (iii)
- (d)
(i), (ii) and (iii)
Why are the electric wires used in homes usually covered with materials like plastic or rubber?
- (a)
To prevent rusting
- (b)
To make handling easier
- (c)
To prevent shock and short circuits
- (d)
To make them look beautiful
Why is a switch used in a circuit?
- (a)
To save energy
- (b)
To complete or break a circuit
- (c)
To prevent electric shocks
- (d)
To make the bulb glow easily
Which of the following does NOT conduct electricity?
- (a)
Aluminium
- (b)
Salt solution
- (c)
Ceramic articles
- (d)
Silver
Which of the following energy conversions take place in a torch?
- (a)
Electrical⟶chemical⟶light
- (b)
Chemical⟶electrical⟶light
- (c)
Electrical⟶light⟶chemical
- (d)
Light⟶chemical⟶electrical
Which metal is used for making electric wires?
- (a)
Graphite
- (b)
Iron
- (c)
Copper
- (d)
Zinc
Identify the symbol of a fuse.
- (a)
- (b)
- (c)
- (d)
In a circuit with one bulb, another bulb is added in series. What happens to the bulbs when current is passed?
- (a)
They do not glow.
- (b)
They glow less brightly.
- (c)
They glow more brightly.
- (d)
They get fused
In which of these circuits will the bulb or bulbs glow the brightest?
- (a)
A simple circuit with one bulb and one cell
- (b)
A simple circuit with one bulb and two cells
- (c)
A simple circuit with two bulbs and one cell
- (d)
A simple circuit with two bulbs and two cells
Identify the circuit diagram in which the bulb does NOT light up.
- (a)
Only Pand Q
- (b)
Only Q and R
- (c)
Only Rand P
- (d)
P, Q and R
Which of the following cannot be used in electrical wires?
- (a)
Copper
- (b)
Silver
- (c)
Aluminium
- (d)
Iron
Which components are required to make a simple electric circuit to light a bulb?
- (a)
Wires and a switch
- (b)
A cell and a switch
- (c)
A bulb and wires
- (d)
Wires, a cell, a bulb and a switch
Which of the following is the symbol of an electric bulb?
- (a)
- (b)
- (c)
- (d)
Why is copper NOT used as a filament?
- (a)
It produces white light
- (b)
It has a high melting point.
- (c)
It is a good conductor of current.
- (d)
It produces heat.
Which one of the following is the correct grouping of different materials according to their electrical conductivity.
- (a)
Electrical Insulators Electrical Plastic, wood Mercury, tungsten - (b)
Electrical Insulators Electrical Conductors Carbon, steel Iron, paper - (c)
Electrical Insulators Electrical Conductors Copper, gold Nickel, clay - (d)
Electrical Insulators Electrical Conductors Iron, rubber Silver, plastic
Why doesn't a bulb glow even if the correct connections are made?
(i) Battery is dead.
(ii) Filament is broken.
(iii) Switch is closed
- (a)
Only (i)
- (b)
Only (ii)
- (c)
Only (iii)
- (d)
Only (i) and (ii)
Look at the figure shown below
Why is sealing wax filled in the space between the terminals of a bulb?
- (a)
To prevent the escape of air inside the bulb
- (b)
To prevent the contact between the two terminals
- (c)
To have a better contact of terminals with one another
- (d)
To give support to the supporting wires holding the filament
What does a battery contain?
- (a)
A minimum of two terminals
- (b)
A minimum of three terminals
- (c)
A cell and a switch
- (d)
A bulb and a switch
Look at the circuit given below.
It consists of a cell, a bulb with two terminals X, Y and wires. P, Q, Rand S are positions marked. What is the direction of the flow of current?
- (a)
PQRS
- (b)
PSRQ
- (c)
PRQS
- (d)
SQRP
What is the source of electricity in the satellites?
- (a)
Dry cells
- (b)
Dynamos
- (c)
Solar cells
- (d)
Accumulators
Look at the figure given below
What do you observe when the switch is closed?
- (a)
The bulb lights up
- (b)
Electrical energy is converted into sound energy.
- (c)
The bulb does not glow
- (d)
Light energy is converted into heat energy
Electric cells can be used in
- (a)
alarm clocks and wrist
- (b)
radios and transistors. watches.
- (c)
cameras.
- (d)
all of these.
An electric bulb may not glow if
- (a)
the bulb is fused.
- (b)
the filament is broken.
- (c)
the crcuit is broken.
- (d)
all of these.
Which one of the following is a good conductor of electricity?
- (a)
salt solution
- (b)
mercury
- (c)
graphite
- (d)
all of these
Which one of the following is an insulator?
- (a)
dental floss wire
- (b)
wood
- (c)
mica
- (d)
all of these
A screw driver used by an electrician has a
- (a)
a plastic handle.
- (b)
a metallic working part.
- (c)
insulator.
- (d)
all of these.
Pick out the odd one.
- (a)
Zinc
- (b)
aluminium
- (c)
iron
- (d)
bakelite
Whether a material is a good conductor or a bad conductor of electricity can be easily tested by putting the material in a circuit and checking the flow of current. Which of the following will not allow a bulb to glow, if it is made a part of the circuit?
- (a)
aluminium foil
- (b)
lead of the pencil
- (c)
cork
- (d)
sewing needle
Which one of the following is incorrect?
- (a)
Insulators as well as conductors are required in electric circuits and devices.
- (b)
Electric current is a flow of electricity in a conductor.
- (c)
The first Voltaic cell used copper and zinc rods kept in a solution of dilute sulphuric acid.
- (d)
None of these.