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State whether the following statements are true or false.
$(a)$. An electric motor converts mechanical energy into electrical energy.
$(b)$. An electric generator works on the principle of electromagnetic induction.
$(c)$. The field at the centre of a long circular coil carrying current will be parallel straight lines.
$(d)$. A wire with a green insulation is usually the live wire of an electric supply.
$(a)$. "An electric motor converts mechanical energy into electrical energy."
This statement is false.
Reason:
An electric motor does not convert mechanical energy into electrical energy. An electric motor converts electrical energy into mechanical energy. When an electric current is passed into a coil placed in a magnetic field, it starts rotating.
$(b)$. "An electric generator works on the principle of electromagnetic induction."
This statement is true.
Reason:
When a coil is rotated by some external mechanical energy in a magnetic field magnetic flux is changed, then an induced emf in the coil is produced by changing the flux. Thus induced current starts to flow.
$(c)$. "The field at the center of a long circular coil carrying current will be parallel straight lines."
This statement is true.
Reason:
By the right-hand thumb rule, it can be proved that the field at the center of a long circular coil carrying current will be parallel straight lines.
$(d)$. "A wire with green insulation is usually the live wire of an electric supply."
This statement is false.
Reason:
In domestic wiring, the earth wire has a green insulation cover, while live wire has a red insulation cover.
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