Question

Some students set up the circuit shown to investigate how a variable resistor affects an electrical circuit.
If the variable resistance is increased :

• A. Ammeter reading - decreases Voltmeter reading - decreases
• B. Ammeter reading - decreases Voltmeter reading - increases
• C. Ammeter reading - increases Voltmeter reading - decreases
• D. Ammeter reading - increases Voltmeter reading - increases

Answer 1

The correct option is A Ammeter reading - decreases Voltmeter reading - decreases

$R_v=$variable resistance

Current in circuit=$I=\frac{E}{R_v+R}$=measuring of Ammeter

Reading of voltmeter= $IR=\frac{ER}{R_v+R}$

On increasing variable resistance that is $R_v$, both reading decreases.

Answer-(A)