Review problem. a light string with a mass per unit length of 8.20 g/m has its ends tied to two walls separated by a distance equal to three-fourths the length of the string (fig. p16.30). an object of mass m is suspended from the center of the string, putting a tension in the string. (a) (mg)^1/2(b) 1/4(mg x 1000)^1/2 (c) 1/8(5mg x 1000)^1/2(d) none

The answer is 'D' none

Explanation:

In the figure shown we have

From the figure we can see that

Thus value of tension be will be

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current