CBSE Questions for Class 7 Physics Electric Current And Its Effects Quiz 4 - MCQExams.com

The hammer hits the gong in an electric bell because
  • It has electric charge
  • It displays the spring effect
  • It is attracted towards the electro-magnet
  • All of the above
During a doorbell ringing
  • Current always flows in the circuit
  • Electromagnet is always present
  • Striker is always in contact with metal gong
  • Striker always repeatedly hits metal gong
Electric doorbell
  • Always consume power
  • Consume power only when switch is pressed
  • Do not consume power practically and needs only starting power
  • Can't say
Armature is pulled towards the spring when it strikes the gong because
  • The electromagnet gets demagnetized
  • The current flow breaks
  • Spring effect
  • All of the above
What will happen if the striker of a doorbell is kept in a magnetic field in a direction perpendicular to motion of striker
  • Striker Hits Harder
  • Striker rebounds harder
  • More current is drawn
  • No effect
Exposed Electric doorbell can be damaged by 
  • Mechanical damage
  • High Electric currents
  • Humidity
  • All of the above
Match the following
Horse-shoe magneta. Holds the armature in place
Armatureb. Electromagnet
Spring stripc. Passes electric current to the spring strip
Adjusting screwd. Fixed to the spring strip
  • $$1 - d, 2 - a, 3 - c, 4 - b$$
  • $$1 - a, 2 - c, 3 - b, 4 - d$$
  • $$1 - b, 2 - d, 3 - a, 4 - c$$
  • $$1 - c, 2 - b, 3 - d, 4 - a$$
Which of the following symbol is used for capacitance in circuits?
What does this symbol mean in electric circuit?

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  • A C power source
  • D C power source
  • current generator
  • none of these
What does this symbol mean in electric circuit?

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  • Switch
  • Cell
  • Resistance
  • Battery
Which component is this?

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  • capacitance
  • resistance
  • battery
  • inductance
What does this symbol mean in electric circuit?

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  • Transformer
  • Battery
  • Capacitor
  • None of these
When the switch of an electric bell is pushed.
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  • Flow of the current stops through the electromagnet in the bell
  • Current starts to flow through the electromagnet
  • Voltage decreases in the circuit
  • None of the above
Is the symbol of
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  • Plug key
  • Load
  • Heater
  • Bulb
What does this symbol mean in an electric circuit?

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  • resistance
  • capacitace
  • inductance
  • power source
Which of the following is the symbol of ground connection?
While making a battery ______________  of a cell is connected to ___________ of other cell.
  • negative terminal , negative terminal
  •  positive terminal , negative terminal
  • positive terminal , positive terminal
  • neutral terminal ,negative terminal
Which of the following devices can be used to break an electric circuit:
  • Cell
  • Bulb
  • Switch
  • None of these
Why CFL is better in comparison to bulb ? 
  • Because bulb produce heat which results in wastage of electricity and CFL saves electricity.
  • Because bulb produce heat which results in production of more electricity than CFL
  • Because CFLs size is bigger than bulb
  • Because CFL produce heat which results in saving of electricity.
Choose the wrong option
  • A cell is a single unit which converts chemical energy to electrical energy to deliver a voltage while a battery is composed of a number of cells in series to get increased voltage
  • A Battery is a single unit which converts chemical energy to electrical energy to deliver a voltage while a cell is composed of a number of batteries in series to get increased voltage
  • In the combination of cells, cells are connected in such a way that negative terminal of a cell is connected to positive terminal of the next cell
  • In the combination of cells, cells are connected in such a way that negative terminal of a cell is connected to negative terminal of the next cell
The symbol of a switch in a closed circuit:
What is CFL ?
  • Compact Fluorescent Lamp
  • Compact Fluorescent Lamina
  • Complete Fluorescent Light
  • Controlled Fluorescent Light
The given diagram is a torch containing cells. The torch is not glowing when the switch is ON. Now, it is opened to know the reasons. Which of the following statements are correct regarding the reasons?
(i) Bulb of the torch is fused.
(ii) Cells are not connected properly.
(iii) The metal parts of the torch do not make proper contact with the cell.

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  • Only (i) and (ii)
  • Only (ii) and (iii)
  • Only (i) and (iii)
  • All (i), (ii) and (iii)
Choose the wrong option regarding miniature circuit breaker (MCB)?
  • MCB contains a metal that melts when the current passing through it exceeds a certain value and hence opens the circuit
  • Quick restoration of an MCB is possible just by switching on the operation when a breakdown occurs due to the current overload
  • MCB switches off the circuit automatically when the current passing through it exceeds a certain value
  • None of the above
Shivam went for buying a CFL from D-mart, what safety mark he should look for?
  • Agmark
  • ISI mark
  • Trade mark
  • Brand logo
Which of the following circuits will the bulb glow?
An electric bell has a resistance of $$5 \Omega$$ and requires a current of $$0.25\ A$$ to work it. Assuming that the resistance of the bell wire is $$1 \Omega$$ per $$15m$$ and that the bell push is $$90m$$ distance from the bell. How many cells each of emf $$1.4V$$ and internal resistance $$2 \Omega$$, will be required to work the circuit.
  • $$3$$
  • $$4$$
  • $$5$$
  • $$Can't\ be\ determined$$
___________ is used to measure electric resistance in a circuit.
  • Voltmeter
  • Galvanometer
  • Ammeter
  • Ohm meter
When a switch is in OFF position,
i) Circuit starting from the positive terminal of the cell stops at the switch.
ii) Circuit is open.
iii) No current flows through it.
iv) Current flows after some time.
Choose the combination of correct answer from the following.
  • all are correct
  • (ii) and (iii) are correct
  • only (iv) is correct
  • only (i) and (ii) are correct
A switch is an on-off device in an electric circuit.
  • True
  • False
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