Two resistance R₁ and R₂ are connected in series with a battery and an ammeter of negligible resistance. If a low resistance volt-meter is connected across R₁ the ammeter reading.

increases   

Initially the resistance of circuit is R₁ + R₂. When a low resistance voltmeter of resistance R_v is connected in parallel across R₁ the effective resistance becomes 

$ R_2 + \frac{R_1 R_v}{R_1 + R_v} < R_1 + R_2$

  When resistance of circuit decreases, current is the circuit increases.