Electric Current and its Effects CBSE Class 7 | Important Question and Answers

 A.Short Answer Questions


Q1.What is the filament of electric bulb made up of
Ans.Tungsten

Q2.What is MCB Stands for
Ans.Miniature circuit breaker

Q3.Which device is used to measure electric current
Ans.Ammeter

Q4.Electric current is the flow of________
Ans.Electron

Q5.Which metal is best conductor of electricity
Ans.Silver

Q6.A Device which prevent or allow the current to flow through it
Ans.Switch 

Q7.When two or more cells are joined together it forms a
Ans.A Battery

Q8.Fuse wire is made up of alloys of
Ans.High melting point

Q9.Coils of heating devices are made up of
Ans.Nichrome

Q10.Wire carrying current produce
Ans.Heating and magnetic effect

Q11.Connecting many appliances with single circuit m ay lead to_________
Ans.Overloading

B.Long Answer Questions 

Q1.What is short-circuiting? How it occurs?
Ans.When live wire and neutral wire come in contact of each other short circuiting occurs. During this, heat is developed in circuit and melts the conductor. Connecting many appliances with single socket may also causes short circuiting.

Q2.What is electromagnetic induction? Write its applic ation.
Ans.The process by which electric current is induced by moving a conductor in magnetic field of a magnet. Electric generator is based on p rinciple of electromagnetic induction to produce electric current.

Q3.What are the uses of Electromagnet
Ans.Electromagnet is used:
a. Lifting heavy items of iron and steel.
b. To separate iron scrap from garbage.
c. Used by surgeon to remove tiny iron splinters from wounds.

Q4.What is electric bell? Name its main components.
Ans.An electric bell is a simple device which uses an e lectromagnet to produce sound. Some of the important components of an electric bell are
a. An electromagnet
b. An armature
c. Gong
d. Hammer

Q5.What is a difference between open and close Circuit
Ans.Closed circuit is a circuit in which current is flo wing and switch is in closed position. On the other hand, in open circuit curren t do not flow and switch is in open condition.

Q6.What is an Electromagnet?
Ans.When a soft iron piece is placed into the solenoid having current flowing through it. The iron piece behaves like strong magnet. This magnet is called electromagnet.

Q7.Why do we use nichrome in an electric heater?
Ans.Nichrome is an alloy having high resistivity. The m elting point of nichrome is also very high. So, nichrome is used as coil in electric heat er.

Q8.Write difference between a cell and a battery?
Ans.Fuse is a safety device made up of alloy having low melting point. It is connected in series in the circuit. It protects the circuit and electrical appliances in case of excess of current in the circuit.

Q9.Write difference between a cell and a battery?
Ans.A cell is a device that creates potential differenc e in the circuit to flow the current in the circuit. Combination of two or more cell in ser ies is called a battery.

Q10.What is electromagnetic effect of electric current?
Ans.When electric current flows through a conductor, ma gnetic field is produced around the conductor. This effect of current is called mag netic effect of electric current.
Q11.What is electric current? How its flows?
Ans.The flow of current through a conductor is called e lectric current. Electron flows through the conductor due to potential difference.

Q12.What is different between electromagnet and permanent magnet
Ans.Electromagnet lose its magnetic property as soon as current is stopped flowing. Permanent magnet does not require current to show m agnetic effect. Strength of electromagnet is more than permanent magnet.

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