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WorksheetsGrade 7 - Electric current and its Effects
Total questions: 42
Worksheet time: 42mins
A fuse wire is a wire of-
High resistivity and low melting point
High resistivity and high melting point
Low resistivity and low melting point
Low resistivity and high melting point
When current is switched 'on' of a bulb it converts _______ energy into _______ energy.
Electrical, heat
Electrical, light
Electrical, mechanical
Electrical, sound
When current is switched on in an electric bell, it converts _______ energy into _______ energy.
Electrical, light
Electrical, sound
Electrical, heat
Mechanical, sound
Connection of more than one device/ appliance to a single socket is called-
Overloading
Short circuit
Both
A common household device, that do not use an electromagnet in its working, is-
The electric bell
Geyser
Telephone
Loud speaker
The filament of A bulb, is a wire of
High resistivity, low melting point
Low resistivity, low melting point
High resistivity, high melting point
Low resistivity, high melting point
The heating coils/elements of different electrical appliances are usually made from ________ or ________ wires.
1. Copper 2. Aluminum 3. Nichrome 4. Tungsten
1 & 2
1 & 4
2 & 4
3 & 4
When electric current flows through the metal filament of the bulb it gets heated to very high temperature and becomes______ hot and start emitting _______.
White, light
Red, light
White, heat
Red, heat
Which one of the following is the most energy efficient
LED
Incandescent bulb
CFL
The heating effect of an electric current is used in
Hair dryer
A fan
A computer
A combination of two or more cells is called
A button cell
A battery
An electric cell
Truck battery
Substances through which electric charges flow easily are called
Wire
Metal
Conductors
Insulators
Substances through which electric charges cannot move freely-
Insulators
Conductors
Wood
Plastic
Which is true about a cell?
Longer line represent-Positive terminal and Shorter line represents-Negative Terminal
Longer line represent-Negative terminal and Shorter line represents-Positive Terminal
Both line represent-Positive Terminal
Both line represents-Negative Terminal
Full form of-CFL
Compact Flood Light
Common Full Light
Compact Fluorescent Lamp
Compact Flood Lamp
Three bulbs A, B, C are connected in a circuit as shown in Figure, When the switch is ‘ON'
bulb C will glow first.
bulb B and C will glow simulaneously and bulb A will glow after some time.
the bulbs will glow in the order A, B and C
all the bulbs A,B and C will glow at the same time
Which of these following cannot be harmed by electric current
plastic
Rubber
A & B
All of the above
When the switch is on the circuit from the positive to negative terminal is complete
True
False
Wires made from some special materials melt quickly and break when a large electric current passes through it.these wires are used to make
Fuses
Electric fuses
A&B
Electromagnet
·Who was the first person to notice the deflection of compass needle everytime the current passes through the wire.
Hans Christian Andersen
Hans Christian oersted
Hans Christian mandorson
None of the above
A _________ is a safety device which prevents damages to electrical circuits and possible fires.
Battery
Fuse
Wire
none of the above
The amount of heat produced in a wire depends on
Material
Length
Thickness
All of these
Which mark is necessary on electric appliances?
AGMARK
ISI
FICCI
KSK
A device used to measure the amount of electric current flowing through a circuit.
Ammeter
Voltmeter
Resistor
Battery
Current flows through the circuit when the circuit is in the _________________condition.
Broken
Open
Closed
Incomplete
The magnetic field around a current carrying coil
Lasts for three hours
Lasts as long as current flows through it
Lasts till its half-life period
Is permanent
A fuse wire is made up of alloy
Nichrome
Tin-lead
Manganin
Constantan
Copper wires are used as connecting wires because
Copper has very high melting point
Copper wires are very thick wires
Copper wires offer a lower resistance
None of these
The device used to make or break an electric circuit is
Resistor
Battery
Switch
Ammeter
Which of the following cannot be an example for the use of electromagnets
Electric Bell
Doorbells
Oven
Phone
When an electric current flows through a copper wire AB as shown in Figure, the wire:
deflects a magnetic needle placed near it
becomes red hot
gives electric shock
behaves like a fuse
The coil of wire contained in an electric heater is known as
component
element
circuit
spring
How is electric potential measured
Voltmeter
Galvanometer
Ammeter
It cannot be measured= infinity
Where can the key or switch be placed in the circuit?
The left side of the battery
The right side of the battery
Can be placed anywhere in the circuit
Near the positive terminal of the bulb
On what principle is electric bell based?
heating effect of current
magnetic effect of current
What is the full form of MCB?
Miniature Circuit Board
Miniature Circuit Breaker
Multimeter Circuit Board
What is the direction of conventional current flow?
from positive terminal to negative terminal
from positive terminal to positive terminal
from negative terminal to positive terminal
from negative terminal to negative terminal
Identify correct statements. (Select all correct options)
The filament type electric bulbs are power-efficient.
CFLs do not work on the heating effect of current.
CFLs are more expensive than electric bulb.
CFLs consume more electricity than electric bulb.
Electric fuse, when gets heated too much, breaks
electrical appliances
electric current
electric circuit
short-circuit
Which of the following devices work on heating effect of the current? (Select all correct options)
Electric bulb
Electric iron
Electric bell
Fuse
immersion rod
What is true about electromagnets? (Select all correct options)
Their magnetism can be altered
When electric current is switched off, it does not behave like a magnet.
They cannot be as strong as a permanent magnet
Magnetism in electromagnet is natural.
What are the factors on which the strength of an electromagnet depend?
1. number of turns of the coil
2. strength of electric current
3. both 1 and 2
