The current through the `8Omega` resistor (shown in fig.) is

Options

A. 4A
B. 2A
C. zero
D. 2.5A

Answer

C

Explanation

The lower limit is zero volt (0 V) when X is at the lower end
of the `4 k Omega` resistor. The upper limit is the potential differnece
across the `4 k Omega` resistor when X is at the upper end of the `4 k Omega`
resistor. That is
`V= ((25)/(1K + 4K))4K = ((25)/(5)) 4 = 20V`
Thus, the limits are 0 and 20 V.