CBSE Questions for Class 7 Physics Electric Current And Its Effects Quiz 3 - MCQExams.com

An electromagnet is a temporary magnet.
  • True
  • False
In the circuit shown in figure, when the circuit is completed, the hammer strikes the gong. Which of the following force is responsible for the movement of hammer?

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  • Gravitational force alone
  • Electrostatic force alone
  • Magnetic force alone
  • Frictional force alone
An electric bell works on the .......... effect of a current and uses an ..........
  • Magnetic, Permanent magnet
  • Heating, Electromagnet
  • Magnetic, Electromagnet
  • Heating, Permanent magnet
Name one device that uses an electromagnet.
  • Electric bell
  • Barometer
  • Lactometer
  • All the above
Which one of the following heater element is used in electric press
  • Copper wire
  • Nichrome wire
  • Lead wire
  • Iron wire
A fuse is used in an electrical appliance :
  • To earth the appliance
  • To protect the appliance and its cable
  • To change the efficiency of the applicance
  • To change the current rating of the applicance
An electric bell uses ......... shaped electromagnet for its working.
  • L
  • U
  • Bar
  • Circular
Symbol of electric cell is -
The essential requirements for a good heating element are _________________.
  • High resistivity and low melting point
  • High resistivity and high melting point
  • Low resistivity and low melting point
  • Low resistivity and high melting point
What happens to a circuit when the switch is off?
  • The circuit is complete
  • There is a gap in the circuit
  • Electricity flows continuously
  • Electricity flows discontinuously
What is symbol of battery?
What must happen for an electromagnet to have a magnetic field?
  • It must be heated.
  • It must be touching another magnet.
  • It must be lined up with earth's magnetic field.
  • It must be connected to an electrical source.
A __________ is a combination of two or more cells connected end to end.
  • Battery
  • Dynamo
  • Coil
  • Switch
In electric bells, electrical energy transform into ............. energy.
  • Mechanical
  • Magnetic 
  • Sound
  • Light
When the switch of an electric bell is on then electric current in it :
  • Flows and stops in succession
  • Flows continuously
  • First flows in one direction and after sometime in other direction
  • Flows in beginning and then stops forever
What is symbol of switch in 'OFF' position?
Which material is used for making the armature of an electric bell?
  • Soft iron
  • Hard iron
  • Nickel
  • Any magnetic material
The components required to make a simple series circuit to light a bulb are
  • Wires and cell
  • Cell and switch
  • Bulb and wires
  • Both B and C
An electromagnet is a permanent magnet. 
  • True
  • False
What is the symbol of wire in an electrical circuit?
When electric current passes through the filaments of a bulb, it starts emitting light due to:
  • Heating effect of electric current
  • Magnetic effect of electric current
  • Chemical effect of electric current
  • Lighting effect of electric current
What will happen if the strip in a doorbell loses its flexibility?
  • Striker may break if current is large.
  • After hitting the metal gong, it never returns to original position and only a single sound is produced.
  • System of doorbell breaks
  • Both A and B
Why doorbell rings repeatedly when switch is pressed 
  • Because of nature of current
  • Because electrical switch is built in such a manner
  • Because of make and break arrangement
  • Because of slight humidity in the circuit
Working of electric bells is an example of
  • Mechanical effect of electric current
  • Heating effect of electric current
  • Magnetic effect of electric current
  • None of these
(symbol) is -
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  • Electric bulb
  • Switch in 'ON' position
  • Switch in 'OFF' position
  • Battery
This symbol is -
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  • Switch in 'OFF' position
  • Electric bell
  • Switch in 'ON' position
  • Electric bulb
What is the use of flexibility strip in a doorbell?
  • It brings back striker to its original position
  • It supports the motion of the striker
  • It completes the electric circuit flexibly
  • Its a safety precaution
Choose the symbol of a single cell
Which process is applied on a circuit for the working of an electric bell?
  • Magnetization
  • Make and break
  • Both A and B
  • None of the above
Why are switches/keys used in a circuit?
  • To save power
  • To protect the system
  • To control a device
  • All of above
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