Answer:
a) 
b) west end of the bar is positive.
Explanation:
Given:
- emf induced in the bar,

- length of the bar,

- velocity of the bar at the given instant,

(a)
The magnitude of the horizontal component of the Earth's magnetic field(B):
We know:



(b)
Using Fleming's left hand rule we determine that the current is flowing towards east end of the bar i.e. west end of the bar is positive.
Answer:
Series circuit
Explanation:
By definition series circuit is a closed circuit in which the flow of electric current follows only one path.
In a simple electrical circuit (which is a series circuit) where electric cell is the source of power, each component is connected in such a way that there is only one pathway current flows from the positive terminal(+) round to the negative terminal(-) via the external circuit.
Current having only one pathway to flow means that when one of the components is removed, there will be no current flow.
The strength of chemical bonds would be the best answer to this question. Hardness is indirectly related to the strength of chemical bonds. Hardness is the resistance from the destruction of an object itself from a material. Hardness does not need to strength of chemical bonds in order to have this resistance.
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