(a)
`3.4 = 0.04 xx R_A + 0.04 xx 3 + V_1`
=`0.04 xx 2 + 0.04 xx 3 + V_1`
=`0.2 + V_1`
`V_1 = 3.2 V`
Current in `100 Omega, (3.2)/(100) = 0.032 A`
Current through voltmeter `= 0.040 - 0.032 = 0.08 A`
Let resistance of voltmeter is `R_V`
`V_1 = 0.08 R_V`
`3.2 = 0.08 R_V`
`R_V = 40 Omega`
If voltmeter is ideal, `R_V = oo` , no current will flow through it.
`R_(eq) = 3 + 2 + 100 = 105 Omega`
Current in circuit `i = (3.4)/(105) A`
`V_X - V_Y = i xx 100 = (3.4)/(105) xx 100 = 3.23 V = V_1`
(b) (i)
`V_1 = (200//3)/(200//3 + 200) xx 4 = 1 V` : reading of voltmeter
(ii)
`V_1 = 2 V` : reading of voltmeter.
( c)
`p.d` across `300 Omega = 30 V`
Current in `300 Omega i = (30)/(300) = (1)/(10) A`
Current in `400 Omega i_1 = (30)/(400) = (3)/(40) A`
Hence current through voltmeter
`i_V = i - i_1 = (3)/(10) -(3)/(40) = (1)/(40) A`
`p.d` across voltmeter
`30 = i_V R_V = (1)/(40) R_V`
`R_V = 1200`
Resistance of voltmeter `= 1200 Omega`
Voltmeter across `300 Omega`.
`V_X - V_Y = (240)/(240 + 400) xx 60 = 22.5 V`
Reading of voltmeter `= 22.5 V`
(d)
Case (a), `V_A + V_V = 6` ....(i)
Case (b), `2 V_A + (V_V)/(2) = 6` ...(ii)
Solving `V_V = 4 V`
Reading of voltmeter in case (b)
`(V_V)/(2) = (4)/(2) = 2 V`.