Electricity: Magnetic and Heating Effects
Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.
Heating Effect of Electric Current
SubtopicHeating Effect of Electric Current under Electricity: Magnetic and Heating Effects for Grade 8 CBSE.
Preview questions (no answers)
- 1.
The presence of argon or nitrogen gas inside an electric bulb is intended to:
A.Make the bulb colorful
B.Prevent the filament from burning out
C.Increase the current
D.Reduce the light produced
- 2.
Why does the bulb of an electric torch not get as hot as a room heater?
A.It uses more current
B.It has very low resistance and current
C.It is made of wood
D.It has no heating element
- 3.
What happens to the heating element immediately after the switch is turned off?
A.It gets hotter
B.It starts cooling down
C.It continues to glow
D.It melts
Download the worksheet for Electricity: Magnetic and Heating Effects - Heating Effect of Electric Current to practice offline. It includes additional chapter-level practice questions.
Electric Fuse and Safety Devices
SubtopicElectric Fuse and Safety Devices under Electricity: Magnetic and Heating Effects for Grade 8 CBSE.
Preview questions (no answers)
- 1.
To protect a household circuit from damage caused by excess current, a safety device like a fuse must be placed where it can monitor the total current flow. In the following diagram, at which position should the fuse be installed to protect both the bulb and the heater simultaneously?
A.At Point X (Main Line)
B.Only in the wire connected to the Bulb
C.Only in the wire connected to the Heater
D.At the very end of the heater's connection
- 2.
When a fuse blows, it means the circuit has become:
A.Closed
B.Broken
C.Short-circuited and dangerous
D.More efficient
- 3.
Why do we use copper for connecting wires in household circuits?
A.It is a very good conductor of electricity
B.It is a very good insulator
C.It has a very low melting point
D.It is magnetic
Download the worksheet for Electricity: Magnetic and Heating Effects - Electric Fuse and Safety Devices to practice offline. It includes additional chapter-level practice questions.
Magnetic Effect of Electric Current: Oersted’s Observation
SubtopicMagnetic Effect of Electric Current: Oersted’s Observation under Electricity: Magnetic and Heating Effects for Grade 8 CBSE.
Preview questions (no answers)
- 1.
The magnetic effect of current was discovered ________.
A.Deliberately after many years of search
B.By accident during a lecture
C.While studying the stars
D.While inventing the telephone
- 2.
If the needle does not deflect when the switch is closed, what could be the reason?
A.The battery is dead
B.The wire is broken
C.The needle is jammed
D.Any of the above
- 3.
The phenomenon where a compass needle moves due to current is the basis for making an ________.
A.Electric heater
B.Electromagnet
C.Electric oven
D.Electric bulb
Download the worksheet for Electricity: Magnetic and Heating Effects - Magnetic Effect of Electric Current: Oersted’s Observation to practice offline. It includes additional chapter-level practice questions.
Electromagnets: Construction and Uses
SubtopicElectromagnets: Construction and Uses under Electricity: Magnetic and Heating Effects for Grade 8 CBSE.
Preview questions (no answers)
- 1.
The discovery that electric current can produce magnetism was made by observing the movement of a ______.
A.Clock
B.Magnetic compass needle
C.Thermometer
D.Barometer
- 2.
In an electric bell, the hammer is attached to a flexible metal strip called the:
A.Armature
B.Gong
C.Switch
D.Battery terminal
- 3.
If the insulation of the wire in an electromagnet is damaged and the wires touch each other, it might cause a:
A.Better magnet
B.Short circuit
C.Cooler wire
D.Stronger battery
Download the worksheet for Electricity: Magnetic and Heating Effects - Electromagnets: Construction and Uses to practice offline. It includes additional chapter-level practice questions.
Working of an Electric Bell
SubtopicWorking of an Electric Bell under Electricity: Magnetic and Heating Effects for Grade 8 CBSE.
Preview questions (no answers)
- 1.
When the armature is pulled by the electromagnet, which part is hit by the hammer?
A.Contact screw
B.Soft iron core
C.Gong
D.Spring
- 2.
In an electric bell, the magnetism is produced only when:
A.The hammer hits the gong
B.The current flows through the coils
C.The battery is new
D.The switch is open
- 3.
What is the role of the iron core inside the coils?
A.To stop the current
B.To increase the strength of the magnetic field
C.To act as a hammer
D.To provide sound
Download the worksheet for Electricity: Magnetic and Heating Effects - Working of an Electric Bell to practice offline. It includes additional chapter-level practice questions.