The ammeter A reads 2A and the voltmeter V reads 20V, the value of resistance R is (Assuming finite resistance's of ammeter and voltmeter)

Options

A. exactly `10Omega`
B. less than `10Omega`
C. more than `10Omega`
D. none of above

Answer

`1.25 m`

Explanation

Velocity of B when string is in natural length
`= u_(B) = sqrt(2gh) = sqrt(2g) (h = 1)`
Impulse equation
`rArr - TDelta t = m [v - sqrt(2g)]` ….(i)
`T. Deltat = m[v - 0]` ….(ii)

On solving eq. (i) & (ii) `: v = (sqrt2g)/(2) = (g)/(sqrt2)`
`:.` Distance travelled by A begore coming to rest,
`s = 1 + (v^(2))/(2g) = 1.25m`