True/false
Earth is a closed system as far as materials are connected?

Why is earth called closed system with reference to materials.

Will the current flow more easily through a thick wire or a thin wire of the same material when connected to the same source ? why?

Two metallic wires A and B of same material are connected in parallel. Wire A has length l and radius r and wire B has length 2l. Calculate the ratio of the total resistance of parallel combination and the resistance of wire A?

Twelve cells each having the same e.m.f are connected in series and are kept to a closed box. Some of the cell are connected in reverse order .The battery is connected in series with an ammeter an external resistance R and two cells of the same type as an in the battery .The current when they and support each other is 3 ampere and current is 2 ampare when the two oppose each other. How many cells are connected in servese order ?

A conductor of length L is connected across a dc source of e.m.f E. If the conductor is replaced by another of the same materials and area of cross-section but of length 5 L, by what factor will the drift velocity change?

Closed circulatory system is found in:

Give the magnitude and direction of the net force acting on:- a high-speed electron in space far from all material objects, and free of electric and magnetic fields.