Question

A voltmeter of a very high resistance is joined in the circuit as shown in the figure. The voltage shown by this voltmeter will be _____ .
(A) 5 V (B) 10 V (C) 2.5 V (D) 7.5 V

Answer 1

first of all we have to find out equivalent resistance of resistors .
Req = R + R = 2R = 2 × 10 ohm = 20ohm

now use Ohm's law,
ξ = iReq
where ξ is emf of the cell joined in circuit.
i is current through the circuit.
Req is equivalent resistance.

now, 10= i × 20 => i = 0.5 A

now , reading of voltmeter = iR =0.5 × 10 = 5V

hence, option (A) is correct.