In Fig.`6.59`, when an ideal voltmetre is connected across `4000 Omega` resistance, it reads `30 V`. If the voltmeter is connected across `3000 Omega` resistance, it will read

Options

A. `20 V`
B. `22.5 V`
C. `35 V`
D. `40 V`

Answer

B

Explanation

Let `I` be the current in the circuit, then `I xx 4000 = 30 V`.
If voltmeter is put across `3000 Omega` resistance, then reading of
voltmeter is `I xx 3000 = (30)/(4000) xx 3000 = 22.5 V`