# physics

The emf of a battery is equal to its terminal potential difference:
A) under all conditions
B) only when the battery is being charged
C) only when a large current is in the battery
D) only when there is no curent in the battery
E) under no conditions

my answer: d, The chemical potential energy of real battery decreases, it develops internal resistance and therefore the potential difference across its terminals decreases if its current increases.

Four wires meet at a junction. The first carries 4A into the junction and the second carries 5 A out of the junction, and the third carries 2A out of the junction. The fourth carries:
A) 7 A out of the junction
B) 7 A into the junction
c) 3A out of the junction
d) 3 A into the junction
e) 1 A into the junction

My answer: D, conservation of charge
so 7 A out of the junction
4 A in the junction. So three A in the junction to balance the charge.

Thank you

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